Right now I'm finding that Lemmy has more "generalist" communities spread across various instances, whereas the bulk of magazines seem to focus on tech interests at the moment. Nothing wrong with that (I'm here for a reason!), but right now it feels like Lemmy presents more opportunity for discussion on topics other than Reddit or tech or gaming or whatnot. Maybe that's because Lemmy has been around longer--or at least that's my understanding, but I'm new to both platforms so I'm not sure.
On the flip side, kbin has a much more attractive interface, and it feels like there's a lot of potential here. It's still a little janky, as is Lemmy, but the interface probably feels more familiar to the average Reddit migrant.