Honestly the base game is so good that a compromised console port was nothing to scoff at if you couldn't play it on PC back then. Sure it has worse visuals and performance, and for some reason streamlined character building, but otherwise it's a straight port.
The marketing boasted "bonus levels", but if that's not the new tutorial it must have included some levels broken up for memory limitations because I don't remember any other difference. Some online forums mention a pre-order room with some hax items, and an NPC encounter turned into a minor boss fight, but again I have no recollection of that.
The only true difference is the tutorial, which I'd say is better than on PC. If you want to do a "full" run, play the tutorial on Xenia, then switch to the PC version and start over. There's zero reason to play on console now, but if you're familiar with the PC game the Xbox tutorial is a nice curiosity.