Well, the styles seem to be, at least: gaze into one genre and listen to it split into dozens of others; rinse, repeat.
I stumbled across the term "shoegaze" used to describe a style of music. (Wonderful term, inventive linguistically far more than the music it labels, I think.) It served yet again to remind me how wide the world of music is and how narrow my own tastes. I imagine that once past a certain age — 25? 32? — everyone loses their grip on what's current in the music scene. For one thing, styles pop into and out of existence with the unpredictability of muons. And for another, there are almost as many style as there are species of beetles — which goes to show, I suppose, that God has "an inordinate fondness" for tunes too.
To give you a graphic sense of the variety of popular or contemporary music, I'll show you a chart by a blogger named Jonathon done up, he says, in 16 hours of work, showing the main species — no, genera, more likely — of music in America during the 20 century and their rough interrelations. There are only 80 styles here, but even so the chart is humungous, so you'll need to click on the graphic below to read it:
It seems that every one of the more recent styles will fracture, on examination, into sub genres, and sub sub genres — until these marry neighbouring sounds and morph into new fecund families of music. The shoegaze I referred to earlier (you can listen to a clip here — Ride, courtesy of Wikipedia — because talking about music without listening to it is . . . perverse, somehow) became in some cases post-rock or trip hop and apparently popped up again as nu-gaze (natch) and blackgaze.
Take wonky (a.k.a. aquacrunk or purple sound), for another example. According to Wikipedia, it is (was?) a fusion of dubstep and glitch hop with secondary influences from idm (sic) and wonky techno. Stepping back a number of levels, you can see in the handy Wikipedia chart below that it's a grandchild of hip hop:
(And wonky beats sound like this.)
Give yourself a treat and dance around inside the incredibly rich and nuanced world of music available to us now. Wikipedia is probably your best bet as a doorway to something unfamiliar, with its List of Musical Styles, numbering upwards of a thousand as world music is folded in. Many of the articles linked in the list will have free samples of the music; and where not, there are usually pointers to examples on YouTube. And while you're poking around, have a listen to a little "downtempo" (Deepecho from Wikipedia) — which emerged from "trip hop" and is similar to "ambient" but with a beat, and is a kind of "chill out music", unless "ambient techno" . . . .