I don't know. I think I'm pretty much the same offline and online. But then again I don't think that's true for anyone, no matter what they may think of themselves. So I guess I'm not totally honest to myself about this.
People usually say I'm really calm (I read that as "slow") and down to earth and yet a bit peevish and hard to approach in real life. And apparently I'm weird but I won't sign that at all. I think I'm really normal, boring guy and my posts reflects that quite well.
The biggest difference is that offline I won't use full sentences and instead I prefer to use grunts and stuff . Online gives a chance to think over what I'm about say, to consider, and to parse my thoughts better. So I often come off more idealistic than what I'm in real life.
And naturally, if you meet me offline, I won't speak English. Or if I do, I do it through thick accent. So that alone makes a huge difference.