I saw the movie in theatres, and to my dismay, the unrated version seemed exactly like the one in theatres. I didn't remember anything being any different.
However, there are a couple special features they threw onto the Unrated DVD that were pretty well done, including a News report section, where one of the guys from Babylon 5 plays a news reporter, and Bruce Boxleiter does the voice of the President. There's also a guy playing the Secretary of Defence that looks just like Donald Rumsfeldt.
More gore.
There really wasn't that much more gore though. The theatrical version was just as gory if I remember correctly.
Of course maybe I'm desensitized to gore after seeing the over-the-top gore from Kill Bill.
I think it's sad that I can say that.
There is more gore. There's a site out there somewhere that details it. There's also more character development, but no one cares aboot that.