Is it an out of body experience or a dream when you dream about flying?

Just a dream. Flying can be interpreted as feeling like you are on top of the world, you must have accomplished something in real life to have that dream (or just feel really good about yourself).

Answer

Surveys show that about 15% to 20% of the population have had an OBE at some time during their life (Blackmore, 1982).

An out-of-body experience (OBE) is characterized by a feeling of departing from one�s physical body and observing both one�s self and the world from outside of one�s body. The experience is quite common in dreams, daydreams, and memories, where we quite often take the external perspective. Some OBEs coincide with lucid dreaming. Some people experience an OBE while under the influence of an anesthetic or while semi-conscious due to trauma. Some people have an OBE while under the influence of drugs. OBEs have been induced by electrically stimulating the right angular gyrus (located at the juncture of the temporal and parietal lobes).* Finally, some people experience an OBE when they are near death (near-death experiences or NDEs).

==new answer== We leave our bodies during the dream state each night. Dreams take place in subconscious mind where there are not the limitations you relate to physically
A dream in which you are flying represents being in control. I remember a dream during my indepth studies of me enjoying flying, but when it came to landing I was awkward, which indicated I needed to work more on control or to refine the process. Being in control is essentially having the ability to respond rather than react to any situation.