Lucid dream VS. Astral travel

I was wondering what *your* personal view is?
Are they one and the same?
Does one lead to the other?
Which do you prefer?
What do you use them for?

I hope the last aren't too personal. Just super curious.
After having a lucid dream "hijacked" by a friend (he began speaking on his own, admitting things that were later confirmed indirectly, and overall had more freewill than I had imagined) several people said that it seemed as if I may have been astral traveling and not LD'ing. It got me thinking a bit about the difference between the two.