http://www.eurogamer.net/articles/ffxiii-retail-version-changes-detailed
"Square Enix has explained what will be different in the retail version of Final Fantasy XIII compared with the recently-released Japanese demo. Crucially, levels and summons will be added to FFXIII, according to a list on 1UP that is compiled from various internet destinations. Battle difficulty will be greatly increased, too, making this "the most difficult Final Fantasy ever", if director Motomu Toriyama is to be believed. And while the demo only focuses on one player, the retail version of the JRPG lets party members be controlled and commanded during battle. We'll be able to see combat from more angles, too. Chain attacks will be vital in the full game, and no longer will characters continue to attack thin-air if they accidentally kill an enemy at the beginning of a chain. Snow will be tooled up at launch and no longer rely on his bare fists, too. There's to be an "item" command added for battles, and more segments will be able to be added to the Time Gauge via a new character growth system. Incidentally, the classic Final Fantasy victory fanfare will be there at launch and Square Enix is considering adding victory poses. There will also be command shortcuts to speed proceedings, plus we're promised dialogue subtitles and a solid frame rate." Controling all the characters will be a major difference compared to what people believed it will be till now, as far as I know.
