Check out the other post I made, that explains it as well as I know how to. I suppose yes it is sweep picking in a way, since you sweep from string to string. I don't know what circular picking.
btw: Since I first posted this message, I've been concentrating heavily on alternate picking, and for anyone in the same dilema I was in when I first posted should know that beginners should learn alternate picking first. My playing is so much more clean and fluid now than it was before. I agree that it is best to learn both methods. I think economy picking has great uses, but usually only in little parts, not shredding through an entire scale or anything.