They are alternate realities so the movies are different.
This should answer it more -
http://answers.yahoo.com/question/index?qid=20080620091559AA5y7fi
I watched the 1st movie when it came out so i watched them all in order of release.
also, other 2 movies?? To watch Solid State Society you need to see Standalone complex 1st and 2nd gig. You need to know about the tachikomas. Shirrow's graphic novels are awesome (manga is a company not the name of the genre)