In the recent James Damore Google memo he says
Google leans toward left and that 'political orientation is actually a result of deep moral preferences and thus biases.'
The question is "is left leaning the same as being liberal" since we see left in Asia/EU to be different than US. Or does US left need Asian/EU right leaning towards left to hold power with liberals.
Disclaimer: 2D Compasses or Linear scales are generalizations and there's much more things at stake than what they represent. Like this: 
The idea of Liberal = Left exists almost solely in the context of the USA, due to the internal drifting factors of political ideology at the beginning of the 20th century.
The basic political compass taken in count in almost every country to define what a party or a person is are State Power and citizen freedom (from Anarchic to Authoritarian) and State Econo-Social status (From Libertarian to Conservative).
A well explained example is that, although the United Kingdom's LibDem party is considered a economically speaking Libertarian party (a small state where private enterprise is highly promoted and taxes are low on most scales), socially speaking, it's center-to-right leaning with many conservative and authoritarian policies when you see their parliamentary voting preferences. That makes it a economically Libertarian (or Liberal, as most of Europe says), Socially authoritarian party.
An American listening to the term "Liberal Democratic party" without prior knowledge of UK politics would expect, instead, a economically restrictive, left leaning social party.
Uk compass of parties after the 2015 elections
If we made a political compass of the main United States parties, we would find out that both the Democratic Party and the Republican Party support similar ideas since late 1920's, with only the means of execution and cherry picked end results being the distorting note.
Oversimplified example: like Obamacare vs Trumpcare, Both just a small patch with not many big-scale differences over a titanic privately run for profit healthcare system.
Given that, the parties and their members had to find a way to distinguish themselves. The term Liberal has changed its coinage from its origins just like most 19th-century-born ideologies, and is usually mixed with Neoliberalism (Thatcherism), a globalized, right-leaning and extreme version of it that rose in popularity during the Reagan and Thatcher eras (late 1970's until mid 1980's).
The current meaning of Liberal in the US is often associated with a milder, soft, more tax-prone, more social spending and more corporate brand of American Conservadurism, whereas Conservative is often associated with a more socially strict, less tax stagnant, more decentralized to the states and more Nepotic brand of American Conservadurism.
The terms Left-leaning and Liberal, hereby, should only we interchangeable in USA's own interpretation on what Left, Right, Libertarianism, Liberalism, Authoritarianism and Conservadurism mean, different from mainland Europe, Uk, Africa, or Asia, just like the same terms in Europe would be different than on Asia ( except, maybe, on ex-colonies).
Finally, and to illustrate how diverse and different is the political "compass" around the world, I'm a citizen of Spain, and I favour a center-left social democrat republican party, not even near extreme left, Libertarian leaning. Me (and my party) are considered as part of the "Left" blob of Spanish parties, to the Left of the centrist Socialist Party (the name is misleading), and to the right and below the populist and extreme-left parties.
This is my compass:
Compared to the US compass, I'm almost an Anarchist, compared to the UK compass, I'm less libertarian than a Green, but slightly more lefty. Compared to a French political compass, I'm as Lefty as Melenchon but way more libertarian.
Left, Right, and Liberal are all terms whose meaning is specific to the country and culture of the people they're used by, and the country and culture of the people who are referred to. So if an American talks about Liberals in France, it's impossible to know what they're actually talking about, unless they specifically clarify what exactly they mean.
Since the question has the United States tag: Left leaning and liberal currently are usually used as synonyms if used by people living in the US talking about politics in the US in recent history (not longer than a few decades back, and maybe not longer than a few decades into the future). There may be subcultures where that assertion does not hold.
In the common American parlance, yes, most people would understand that calling a person or policy 'left leaning' is suggesting a Liberal bias.
However, reducing political philosophies to a single axis muddies philosophical distinction, and even omits any form of a scale to understand what a person or origination is left of. (The 'center', is the naive answer, but what does the center encompass? how is it defined? How far left of the center is left?)
As mentioned by other replies, people in other countries would have differing interpretations of what left is. However, it is even more confusing than that. Differing groups in the US have conflicting opinions about what is left. A progressive Democrat might view the policies of former Presidents Clinton and Obama as Neoliberals and 'center', but an ultra-conservative might describe the same policies as 'far left'.
Left-leaning and liberal are indeed the same thing in the US, or at least they are in day to day speech.
(Note that terms can have a very different meaning in other countries. In France for instance, we call "(ultra-)libéraux" (liberals) what they'd call (ultra-)libertarians in the US.)
Question is "Is left leaning same as being liberal"
Short answer: NO
longer explanation: The ideology of right and left evolve and "localize" according to culture and goe-political needs. I.e. in US, so call "democrat" is actually "right leaning" that support neoliberalism endorse by the republicans.
Unless one are talking about "original left vs original right", otherwise you will see all sort of "confuse-leaning".
In fact, unlike mathematics, both fundamental ideology (right and left) contains some flaws when come into execution.
Original left seek for society equality, restrict establishment power upon citizen. However, to achieve equality, a strong institution is required. This introduce a new class issues (rulers vs citizen).
Original right looks forward to preserved establishment authority, anti any progressive movement enact by the left. But technology and knowledge advancement eventually challenge the establishment/market leader(as in capitalism).
In that context I think that the term liberal leaning means preferring the US Democratic party positions and politicians over others. It does not seems to infer any specific ideology itself, but rather uses liberal in an epithet manner that Ronald Reagan is often credited with coining.
The terms liberal and conservative have taken on their own meanings in the US that seem to have diverged from their original meanings.
Liberalism is a political philosophy or worldview founded on ideas of liberty and equality. Liberal philosophy generally emphasizes liberty, individualism, and support for limited constitutional government. In the United States, "liberal" generally refers specifically to social liberalism. SOURCE
Conservatism is a political and social philosophy that promotes retaining traditional social institutions in the context of culture and civilization. By some definitions, conservatives have variously sought to preserve institutions including religion, monarchy, parliamentary government, property rights and the social hierarchy, emphasizing stability and continuity.
I think few people would argue that either dominant US political party actually promotes the values of the ideology they purport to espouse.
The US has different meaning of "liberal" than the rest of the world. Here in Russia "liberal" means right-wing.
The much-upvoted and accepted answer is very detailed and sophisticated but I wanted to attempt a simpler and more generic answer for the benefit of readers like myself who are relatively new to the field of political discussion.
I am Indian and while the socialist 'Left' on the political spectrum here is indeed more liberal than the traditionalist, neo-nationalist 'Right', the most liberal political movement in India is arguably the 'middle path' represented by the Congress Party whose political position is described in the introductory data as "centre-left" by Wikipedia. That just means that even if common interpretations of 'left' and 'right' do not differ much from nation to nation, there can be a very wide difference in the interpretation of what is 'liberal.'
Specifically in the USA context (though I am by no means an expert, and very much open to being corrected) the 2 terms 'liberal' and 'left-leaning' seem to be used interchangeably in ordinary discourse. I was able to find this article which lists out the political positions that tend to appeal to 'liberal' or 'left-leaning' persons:
You are concerned with individual rights & liberties. You are often in favor of government intervention and government programs (pro-regulation). You lean toward the monitoring of business. (...)
A left of center or "liberal" individual tends to philosophically believe in a majority of these political positions. [list of political positions follows.]
I am pointing out this article simply as a random example of the common practice of using 'liberal' and 'left-leaning' interchangeably. But why is this done?
In general, 'left-leaning' implies more socialist political views while 'liberal' would indicate support of 'progressive social ideas' as in Democratic party. In other words both 'liberal' and 'left-leaning' would indicate a leaning away from conservative politics as represented by the Republicans.
Socialism in the USA has often been a controversial political movement enthusiastically supported by a small but significant minority of the population, and a simplistic representation of the spectrum would place socialism at 'left', Democrats in the 'middle' and Republicans at the 'right.'
USA -- a crude spectrum from left to right:
[I am not even including far-left and far-right here]
(Left) Socialist -- left-leaning -- liberal -- Democrat -- right-leaning -- Republican (Right)
However, the Democrats are a major established party with supporters from diverse backgrounds, and many of these supporters are likely to have very liberal attitudes to politics and society. So 'liberal' is nicely placed between 'socialist' and 'democrat' such that 'liberal' is closest in USA to 'left-leaning' on the middle side of the political spectrum. That is why the terms 'liberal' and 'left-leaning' are often found used interchangeably in ordinary discourse.
An interesting question and one that most often confuses people such as the belief that nationalism (nazism) is right leaning. Liberalism is an ideology. That is a belief in a certain group of principles that affect the persons philosophy in all aspects of his life. However, left and right leaning are political forces that only have meaning when comparing one to the other and are subjective depending on the country and time.
Ideology of liberalism comes from the belief that everyone needs to be free and equal. This is ofcourse a simplification of social liberalism. Wikipedia has a nice article on what liberalism is. How this differs from other ideologies is in the equality of persons. Everyone must be treated the same.
From the wikipedia article: Modern American liberalism is the dominant version of liberalism in the United States. It is characterized by social liberalism,[1] and combines ideas of civil liberty and equality with support for social justice and a mixed economy.
In the American point of view of recent history, the left of center party (Democrats), has chosen to take on more of the liberal beliefs and throughout history has been the party where those belief are better served.
Back to basics: what is the political spectrum. If you imaging two vectors pointing away from each other originating at the origin you can call the origin the "center". To the right you have political forces where the further you leave the center the more political power is focused on the individual. For example, in the US, the further right, the more political power leaves the federal government and goes to the local governments. Go far enough and you have homes where each house has a ten foot fence where family members will man machine guns at the cornersl
Going to the left and the (again, this is the US perspective) federal government will have more and more power and the local government less. Go far enough and you have to ask the government permission to stand up and do biological functions.
Now ideologies, especially throughout history will jump the center and go to the other side. For example, did you know that civil rights was once right of center? It makes sense when you see that at the time, the center was extreme federal power and getting to allow the local governments more powers meanth being right of center. Local governments wanted abolition, federal and states did not.
Presently, the ideology of liberalism is best served by those left of center, since only with a stronger federal government will the ideals be fulfill.
Here is another thought experiment to show my argument: Freedom for recreational marijuana has been a long term liberal issue, why is there no fear that it will be overturned in the current era. Contrast this with the other liberal issue, non-gender bathrooms, why is there fear that it will be overturned? The facts are that the current adminstration is removing itself from this issue and letting the states decide, just like marijuana. From a point of view, both issue appear to have its best chance by being right of center.
I appreciate the comments as it seems I did not get my point accross. On the topic of authoritarian ideology. I did not discuss that at all. Both the left and right of the spectrum in mainstream America do want government. The contrast is which government should be stronger, the local or the federal. Which one is more authoritarian, it depends.
Far-right and Far left I discussed simply as a contrast and to emphasize, that: No, liberal and left leaning are not always the same thing. It can change depending on time and society. This is because the center point changes depending on the society.
A good contrast is how do you reconcile the Southern (US) left of the 1860s with the liberalism of the current era. You cant because it was not liberalism as described. However, politically the south was left of center. The proof is how fast the confederate states became federalized and how important the state govenment was and not the local municipal governments.
