On chip cache, FSB speed, Memory speed, better graphics etc... But as Apple ramps the ibook line the gap closes significantly. If I was in the market right now I would get the 12"ibook for $999. It currently spanks my 12"powerbook at a fraction of the price I paid. The only drawback is that the 12"ibook does not have a DVD burner but you can add an 8xDual Layer burner for $200 from many aftermarket sellers and still come in cheaper than the 14"ibook and save the extra weight.