Music is a quite distinctive from audio, as music is formed with art and audio including silence as well. Audio cannot be used as an entertainment medium whereas music is widely accepted as one of the greatest entertainment media across the globe.
There are a few things to differentiate between "audio" and "music":
- audio might include "chirps and tweeps" for e.g. notifications which one wouldn't count as music
- the term "audio" also often is used for speech. Generally, "audio" is "everything you can hear", and "music" is a more specific part of it
- audio often is rather low-fi, using lower bitrates, higher compressions, and due to that has lower "sound qualtity" as that's sufficient here. While the same could be done to music, that would be like putting 8 people in a Smart: no fun in the long run, and you certainly won't enjoy it :)
Read more about music in Wikipedia