It's actually an interesting question to me. I am spoiled and have two rooms in the house that are "mine". My living room is my "sewing room" and that's what I call it. Upstairs I have a spare bedroom that is my "art studio" which is where I do my drawing, painting, beading, papercrafting, and polyclay sculpting. It's also where my PC lives.
Why is one a "room" and one a "studio"? I don't really know, it's just what sounds right, I guess. Or maybe it's because the bedroom next to mine upstairs is my DH's "music studio" so in my mind that part of the house is where the 'studios' are. It's not something I consciously decided.
DH & I are working on converting our last "spare" bedroom into a work space so I can move all my old broken sewing machines out of my sewing room and DH can move his old broken radios out of his music studio and we can work on them in there and share some tools and such. I have been referring to that room as the "mini shop" or "workroom", we'll see what name sticks! ("mini" because the room is rinky dinky, only 9' square, minus a notch for the door - probably designed to be a nursery.)