The resolution is ridiculously low on Xbox 360, it's barely HD (600p) and runs at 40fps on average. Seems like it pushes the old console a little bit too much. That's going to be the main difference.
40fps seems adequate to be playable, not stellar.
What they are calling "campaign mode" is really a structured series of multiplayer online chapters you can optionally play. There is no single player campaign at all.
I imagine not building a campaign mode reduces the amount of work put into the title by 50%, or substantially.