What is the difference between a “rated” and “unrated” version of a movie?

Unrated is not edited, rated is edited, get unrated and rated version of Spun and you will see swear words bleeped out and nudity covered up.

I have baught lots of unrated and rated movies and most of the time I dont notice a difference in the film… but some times you will get the option to watch the movie with alternate endings wich would be unrated do to it not being in the theatrical release which means there is unrated materal (Violence, Nudity, Language…) things of that source.