Look at page 41 and 46. There you will find the difference:
http://download.intel.com/design/mob...s/25261203.pdf
The 478 pin version of the 479, is called the Micro-FC
PGA, and the 479 pin version of the 479, is called the Micro-FC
BGA.
And the u-FCBGA has a NC pin on it for some reason, so it actually only has 478 functioning pins, but 479 gold connects.