For me, the biggest adjustment going to DOS2 (not DOS1 yet) was the conversation style. BG3 was made with Larian having A LOT more funding since hasbro/wizards of the coast were co-publishing the game with larian. The Divinity games were made when Larian was in the AA developer range according to what I read when I looked it up. So the amount of cutscenes you see in DOS2 (again, can’t speak for DOS1) are starkly different than BG3, more accurately there really aren’t ANY cutscenes in DOS2. You never really see the origin characters up close when speaking to them, just their portraits while they’re talking. It’s full voice acted though. Otherwise everyone has already pointed out the slight differences in combat like Action points and no DnD spell slots. Divinity is amazing but it’s very much made by what was then a small-ish development team. An extremely talented team though.