I think the difference is that it’s possible to actually engage with the community on Lemmy.
On Reddit if I see something I have a story or thought on there are already 5000+ comments. The only people responding to me are trolls and those with nothing to do but look for a fight.
On lemmy there might be 50 comments in 10 threads. Conversation can actually happen.
It’s the difference between chatting at a party and shouting at a concert.