[Cavernio]

This is a much more complicated question for me than it should be.

My personality has changed a lot in my adult/teenage years (mental illness will do that), and what I portray on FFR and other forums is different from what I portray in online games in-real-time.
On forums I come off as a pretentious douche. In general I love debating and arguing and analyzing and being contrary when the 'other side' of the argument has a good point (devil's advocate-like). I love stirring up the pot and trying to make people view things from a perspective that they may not have thought of. Forums are the pretty much the ~only~ place I do this, although there's the odd person I can argue with with ease. (But even then it can end badly.)
But like Reach and Dossar and Zager, the vast majority of the time I'll just be like 'oh yeah' IRL to someone who's being dumb or incredibly closed-minded, and will want to change the subject.

You'd also be surprised at the amount of time it takes me to make event he simplest of forum posts. IRL it's all got to be pretty instantaneous, so even if I do get into a debate, I'm often going to lose horribly and not be able to make my point at all. My random bouts of stuttering don't help, and neither does my incredibly ability to forget even the simplest of words. Deabting IRL often ends up with interruptions too, which just is no good for a proper discussion of something.

I can actually be funny IRL and in real-time chat if I'm in the mood. I like making borderline inappropriate jokes. Stuttering and forgetting words sometimes ruins these IRL though too, *grumble*.

Overall I'm more outgoing online.

@binary fission: I'm a nicer person in person not just because I'm held accountable then and there, but I also perceive that people will take things less personally online in a forum setting.
Also, how many times have you had an fight IRL and then the next day feel badly about how you reacted and think, hey, maybe the other person had a point? Real-time interactions are just absolutely horrible for making someone take a step back and think logically about something, including myself. My own experience is that I can be a lot more cool-headed online so that accountability isn't as much of an issue because of it. Maybe I erroneously think other people are the same way too.