I think it's upside-down to a Stop, in that the rope clamping is performed at the top bobbin as the rope exits, rather than the bottom bobbin. Also as its handle is much longer and better-shaped, it's way less painful to use.
Although I use a Stop, I hate its operation - a better-designed handle would be a help (why can't they do that?), but also would remove the danger of your fingers opening the catch plate as you squeeze the handle. Definitely a device in need of a redesign, IMO. I do appreciate the locking function, but try it on 9mm, and it doesn't work so well.
I dropped a massive shaft recently on brand-new 11mm Spanset bagged up beneath me, and I may as well have been on a rack, as there was no 'stop' at all. Mind you, it was one of the smoothest descents I've ever had.