Which one is which, and how can you tell?

Context: I read Main much more than Discussion, due to time constraints and my perception that Discussion is less interesting in bulk. I tend to comment rarely, and thus I pay attention to those comments. Which means that something in Main is more likely to have comments from users like me than something in Discussion.

I’m not sure exactly what you meant, but I thought you meant Main gets more “casual” users and Discussion gets better, well, discussions because of the very active (non-casual) users are more predominant there.

My impression differs with regard to the latter, as I'd expect the very active posters to be mostly everywhere and the high-quality lurkers (which are "knowledgeable insiders" but comment rarely, and provide diversity to a discussion) are mostly in Main. It's probably true that we get more “newbies” in Main, but maybe the voting works better at hiding them for me.