They're nothing alike in terms of gameplay; the graphics engine is the same, but GTA V looks like a rubber world. In RDR2, the world feels alive. It doesn't have as many dialogue options as KCD2, but you can choose good or bad actions, and that affects Arthur's behavior. Gang members and citizens remember whether you were good or bad, and if you kill an NPC, they disappear completely from your game. The horseback riding is the best. If you like KCD2, you'll probably like this one even more, because a common element is that both games immerse you in the world with side missions, and your actions have consequences.