The real difference between an R-rated and an NC-17 rated film? Sex. In fact, the term “NC-17” was first created in 1990 as an artistic alternative to the X rating, long associated with pornography. So, if a movie has a drawn-out intercourse scene or shows full nudity, the MPAA will brand it with the NC-17 — usually condemning the film to box office suicide.
Here's a history of the three movies in all of Oscars history that have scored noms despite their X ratings — and the one movie whose Oscar dreams were almost dashed by the MPAA.