Well they cut back the amount of GR points required to get to the same levels. So you don't have to spend as much time going through quests. They also cut back on the amount of materials required to bind an item. So it is easier to make things. They also changes how certain weapon types work.

Combat has been retooled as well. Your action wheel is full the moment you draw your weapon, no waiting. I think the action wheel recharges faster. Most skills no longer require AC, but MP to use. I believe MP pools have been increased as a result. Mages have AC convert to MP skills. New skills have been added, others have been removed. Equipment enhancement stats have been changed significantly.

I can go on in more detail if you wish.