Ways that this is different than real life for me:
1. People are coming on here to discuss what is rude. So whereas, in real life, if somebody told me "I did X,Y,Z today" I would never say "Oh X is totally rude." But that's the very nature of the site, so it leads to people criticizing each other in ways that we wouldn't in real life.
2. People frequently come on here to talk about other people's rudeness. So for me, if you're going to come on here and point the finger at someone else, I'm going to be on the lookout for ways that YOU caused the rudeness, because that is the only thing you can really control.
3. We're here for information. So when people ask, "why do people do/think/say X??" I'm more likely to tell them "I think X because ..." in order to be informative. Sometimes X or my reason is politically incorrect and is not something I would normally share. But I'll share it here because I'm willing to give people more information. But this is an easy way to offend other people.
Thought I'd add ways that I'm more polite on here:
In real life I make a lot of snarky and sarcastic comments. I do my best to leave them out there. I remember another thread a while back where one poster wrote the same thing, like 15 times, every other post. In real life, I would have been like "Yeah, we got your point the fifth time you told us." On here, I keep it to myself.