I was watching a Fons & Porter episode a few years ago and they were talking about this very thing. Mary Ann Fons stated that she thought the rule was this: If your sewing machine sits out for more than 24 hours, then you have a studio; if you have to put it away after each sewing session, then it is a sewing space" I don't know how true this is because I have a little 9' X 10' room with a walk-in closet and most of the time I leave my sewing machine up on my sewing table (even though I have a cabinet to put it away in!) And I also have to move my machine often as this room is also my computer room. All (okay, almost all) of my fabrics and sewing supplies are in this room. I don't refer to it as a studio, I call it the "Sewing Room"