Even something as basic as chords or speed. Would there be fast, jaunty music? Slower, more poetic ballads?
The topic of medieval music is obviously a big one so more answers are certainly welcome but here's a few older ones by /u/nmitchell076 and /u/erus that talk about bardcore as a concept and then about the kinds of genre in medieval music.
https://www.reddit.com/r/AskHistorians/comments/3m27yk/what_was_medieval_music_like?sort=confidence