People say that you don't dream in comas, and apparently David Chase said in interview something along the lines of "I wouldn't call those dreams".
The Sopranos hinted at the paranormal before (Paulie's visit to the psychic), so is the coma dream supposed to be an actual paranormal experience, or simply a dream of some sort?
I think the intent was more "out of body near death experience". When Paulie is droning away to Tony, in his "dream", or whatever you want to call it, it comes across as a loud murmuring voice through his motel room's wall. When Meadow is begging for him to come back, Tony hears her, and maybe her voice is the only thing that cause him to "turn away from the light" (going into the house), and coming back to his body.
They're playing a little fast and loose with out of body experience, but when you are in a coma, you are NOT technically sleeping, so I suppose it would have to be considered something different than a normal "dream".
I'm pretty sure I've heard the term "coma dream" used before.