I think i can help u guys since these are the genres that i enjoy the most :P
Trance music is very repetitive, usually lacks melody, and has simplistic drum rhythms that go boom-chick-boom-chick for the entire song. Basically, you cannot "really" dance on trance music, whereas, you listen to it and enjoy the different beats/voices it carries.
Trance Example
http://www.youtube.com/watch?v=VFuLa...rom=PL&index=3
Trance Dj's: Armin, Tiesto, Paul Van Dyk, Sander Van doorn, etc...
On the other hand, house music is music on which u can dance to, it carries bass more than trance music does and often has vocals.
House example:
http://www.youtube.com/watch?v=UHWp4_wCpjM
And the best, for me, is electro, i dunno how to explain it but here is a sample.
Electro Example
http://www.youtube.com/watch?v=4k8pz...A28D6B&index=0