Something to do with new processor clock speeds at 2.75ghz and the WLAN (PIFA rather than IFA).
http://www.pc-magazin.de/news/ps4-cuh-1115a-details-leak-fcc-playstation-4-sony-2351384.html
If they bring out a new model with upgraded dual-band WiFi I will be seriously peed off. it's a disgrace that it didn't include it in the first place.