The directors cut vs the original cut

Rating: Null/10 (12 January 2006)

This may have, and probably was already posted, but I just need a quick answer, so I didn't find any need to spend a lot of time look through the rest of the threads.
If you have seen it, does the Director's cut include all that was in the original cut version, plus more or is it just something different, that doesn't include what was in the first release?
I just need to know this because I haven't bought the movie yet, and I was wondering which one would be worth more to buy, the first release or the directors cut.
thanks in advance.