Word for the opposite of electronic music

Spotify has a category called Acoustic Rock. (Amazon Music also has this category.)

Guitar World has an article entitled The 25 Greatest Acoustic Songs in Hard Rock.

EDIT Note that the songs mentioned in the "25 Greatest Acoustic Songs in Hard Rock" include Stairway to Heaven (and many others), which has a distinct minority of "acoustic song." The OP might consider a techno song with acoustic guitar to simply be techno. /edit

You could distinguish your electronic / non-electronic dichotomy as:

Rock / Acoustic Rock

or

Hard Rock / Acoustic Rock

EDIT The Beatles are, by definition, Rock. But how would you classify the track Blackbird (on the White Album)? It consists of acoustic guitar and a single vocal. I think it would be natural to categorize the entire album as Rock, including "Blackbird." If the OP requires the precision to call that track Acoustic Rock or Soft Rock or even Folk, then the OP will need the additional categories. /edit