Obviously also, it comes down to taste. If you are a big fan of a slasher movies, having two slasher houses would be awesome, and they would feel different, even though if you squint they both are similar (villain with weapons tries to kill people). I would say Terrifier and Scream, for example, would have very different vibes. But, I can appreciate that if someone liked slasher movies less than I do, having both would seem kind of duplicative. Same thing for post-apocalyptic - since that is not my favored subgenre, my kneejerk reaction is to say TLOU and Fallout would feel duplicative. But I think you are probably right they could feel very different, especially the more you knew about the properties and appreciated what they were going for.