"Acoustic" as a descriptor for instruments is a retronym (like "analog" for a watch) that came into widespread use only once electric and electronic instruments were invented. It means an instrument that is designed to be played without any electricity involved --so in other words, at one time all instruments were acoustic.
"Unplugged" is a bit different, in as much as it means taking music that was originally composed or played on electric and electronic instruments, and replicating it with all acoustic instruments. The term was popularized by the popular MTV series of the same title, featuring famous rock musicians playing all acoustic sets featuring their own work. The concept was a bit of a backlash against the heavily produced electronica of the 80's and early 90's, as well as serving as proof that famous musicians could sound good even without studio magic. The Unplugged series yielded several notable hits, including Eric Clapton's bluesy "Layla", Mariah Carey's (cover of) "I'll Be There", and Nirvana's "All Apologies."
All "unplugged" music is acoustic, by definition, but not all acoustic music is "unplugged." Classical music, for instance, is acoustic, but not unplugged. "Acoustic" is more of a neutral modifier, it's purely descriptive. "Unplugged," on the other hand, is more of a marketing term, it has deliberate connotations of authenticity, and carries implications of genre.
Unplugged is usually associated with music that was originally created and played plugged in, more often or not associated with heavy metal and rock songs as the difference between the original loud song to the gentle and usually slower song is so radically different.
Links to follow due to char limit.
– Walkerbo May 25 '19 at 06:20All in all this is an interesting topic however there is no definitive answer that I can find that explicitly rules one in or out.
– Walkerbo May 25 '19 at 06:20