I believe it's in the details one observed.
Generally speaking when it comes to so called "out of body" experiences people are able to relay discussions that took place or state something that took place while they physically could not have been a witness to.
Dreams however are rarely about events that are actually taking place in those very moments while we were asleep. We usually dream about things that have happened or may happen and sometimes we dream about things we hope will never happen! (Nightmares). :-)