I think there is one difference in the structure: in TW3, the regions were opening one after the other: White Orchad, Velen, Novigrad and Skellige Isles, each with increasingly difficult encounters. In CP2077, I understand the whole world is directly accessible, and players are surprised to find enemies of completely different levels. That's awkward if there's no hint on how difficult enemies are (maybe there is, I honestly don't know).
While the story in TW3 generally guides you in that direction, you can go anywhere you want at any time. You can even go straight to Skellige if you want, and I've seen people say that it changes dialogue later in the game.