Dreaming is a combined activity of the two elements. Dreams can seem very realistic at times, but always have a touch of unreality to them. Something's just not quite right, there is an odd ingredient. Sometimes the dreamer says dumb things, or there are people who've been out of that life for years, or the person is talking to a deceased relative, or illogical comments are made. Or everything seems natural but the attire is from the Middle Ages.
Dreams also tend to be one-sided.
In them things are happening to the dreamer, or the sleeper is doing something. By contrast, astral projection is a two-sided thing where honest, original feedback of feelings or thoughts are given by another person or spirit. Everything will be of the present time period, there won't be any oddities. Any contact with the greaterbeing is a far more powerful spiritual experience than a dream. But we'll talk about these last two subjects later.