[update] Digital Foundry's broken it down - the short version is
- The CPU is identical to the current PS4's CPU, but it's been overclocked so you get about a 30% performance boost.
- The GPU difference is huuuge - a 230% difference in FLOPs.
- Memory offers 28% more bandwidth, and an additional 512 MBs for devs to play with. [/update]