An OOBE is similar to a NDE, except just not quite as near. Many of the phenomena reported during and after the experiences are similar. Particularly in early OOBEs, there is feeling that one is about to die, or has already died. Many of these sites provide links to other sites as well as articles on the subject.
Some people view astral projection and lucid dreams as different aspects of the same phenomenon.
Others view them as quite separate. I'll let you decide for yourself. Here's the thing. Astral projection requires focused internal enegy, and understanding your chakras will help. You see, the astral body needs energy too.