I was just arguing with a friend over this and we couldn't come up with a valid answer. At first, we thought emo was a bit more mellow than punk music with whiny vocals and kill-yourself lyrics. Upon further investigation, we found that it really was just punk music with the aforementioned qualities. But when we thought about it, some of lyrics of that type have been found in metal, namely Norther, among others, but everyone considers Norther to be metal. So is it the whiny vocals that are the only real trademark of emo music? If so that's a little bit of a flimsy reason to base a whole new genre of music off of...