I think guys tend to do in your face mean things, where as girls will slowly build up methods to mentally destroy someone. It's quite clever how effectively they can upset someone.
And it pisses me off when girls ***** about other girls just because they are better looking.
I also think girls (most evident in high school) regard popularity and it's class system very importantly where as guys will just talk to who they want, girls can be like:' ZOMG! like did you just talk to that geek? ROFLCOPTER!!!1'