Mastakos

So I've been a fan of Glorantha for a few years now, and the games I've played (all one of them) have always used Heroquest. But since the next rulebook will be based on Runequest 2 I thought it would be a good idea to buy the Runequest 2 book. Thing is, Heroquest also my first ever "real" RPG I've ever played, so I am a bit confused by just how much more complex Runequest is than Heroquest. Can anyone give me an explanation as to what sort of rule system Runequest uses?