There's way too many things to list. . .
-tonnes of new content (questlines, as well as dungeons)
-massive FL rebalancing; reworking of Mdef; addition of Crit stat
-Some new in-game systems (jackpot license, etc).
Best for you to lurk official forums, or read the patch notes posted here in the Announcements section.
It's the nature of my circuitry.