2.0's lighting is miles better than 1.0's... mostly because it actually has lighting effects.

As far as stuff they have said on the matter, 1.0 used the same engine as FF13 which makes some pretty textures but is horribly unsuited for MMO games where a ton of characters need to be displayed onscreen. I believe 1.0 could only display 30-40 characters onscreen, both Player and NPC included in that number.

And just FYI there is a Direct X 11 client in the works that is going to be intended for high end PC's.