I'm sure I'm in the minority, but I would not call Neil Young "rock" music, same goes for Bonnie Raitt and The Cure. Not enough good electric guitar turned up to 11 in any of that. Nirvana album was before anyone had ever heard of them so I kinda think that's cheating - I actually didn't know they had an earlier album than Nevermind but I've never been a fan of them.
This was also a year in which Milli Vanilli, Paula Abdul, and New Kids on the Block topped the charts, though, so...yeah.
The list of “rock” sub genres is endless. Folk rock and metal are both types of “rock”.
