90Hz refresh rate. Faster memory tuning (5500 > 6400 MT/s), which is a tangible performance uplift. Torx screws into metal threads for the case so you can open it up safely.
I am simultaneously ecstatic for newcomers who get to enjoy it, and feeling just a bit dunked on. At least I got one of the nice 512 cases.
The big thing for me is the improved bluetooth. I love playing couch multiplayer games, but the connections when using multiple bluetooth controllers have been spotty at best with the current deck.