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.
One thing that was listed in the Digital Foundry video is that they added a wake from Bluetooth feature. That right there is big for a lot of people.