they work a bit differently-clen is often used on racehorses because they can breathe easier on it and has an anabolic effect IN ANIMALS-in humans, it is just a fat burner-the difference in the USA is that clen is not legal and for now, the eca stack is-although if there are more stories about ephedra like the 1 on hbo last nite, I would not expect ephedra to be legal much longer