Ok, I haven't read many of the other replies, but I will tell it to you like this:

An OBE is an "Out of Body Experience." Inherently, there is no difference between OBE and a dream, because an OBE is an "Experience where you perceive life from outside of your physical body." So, even if you are dreaming that you are outside of your body, you are having an out of body experience.

A lucid dream is a dream wherein you know you are dreaming. So an OBE is not a lucid dream unless you know you are dreaming.

But (as far as my own personal opinion) I believe that an OBE is just a dream (not a lucid dream) that gives you the impression of leaving your physical body.