It seems to me you are confusing the premade example setups with the randomized setup.
The 2 pictures you show are premade setups, and both can be used to do a premade setup where the resources will flow well and are good for beginners. But these setups are supposed to be used "as is" with the exact tile and number setup.
The premade number setup is not supposed to be used with random resource tiles as you are suggesting so a 6 or an 8 will never touch, not in the premade setups nor in the 5th edition random setups.
Once you have "graduated" from the pre-made setups, you can advance to the randomized setups. In the randomized setups you can either shuffle the numbers either completely random or place them according to the alfabetic numbering on the back.
If you use the complete random setup you must indeed lookout for 8's touching 6's, which is never allowed no matter the edition version. So if this happens you have to "manually" adjust the numbers. With the alfabetic numbering you can't put 8's and 6's next to eachother when placed correctly.
Why there is a difference between the 2 example setups I don't know, but I would take it as a good thing, and try both example setups before playing randomized setups, both example setups are compliant with the placement rules of the latest 5th edition.
Edit: Furthermore I have confirmed that the 4th edition and the 5th edition have the same alfabetic order on the back of the numbers which is the following:
A=5 - B=2 - C=6 - D=3 - E=8 - F=10 - G=9 - H=12 - I=11 - J=4 - K=8 - L=10 - M=9 - N=4 - O=5 - P=6 - Q=3 - R=11