They pivot.
Jokes aside, the pivots have a turntable heel, metal heel piece, and a short mount.
The PX Ls aren't bad, they are still a nice binding. They have the same toe piece as the Pivots. It all depends on why kind of skier you are. Lighter, less aggressive go with the PX. If you are bigger charging hard and worry about staying in your binding go Pivots. They have a higher elastic travel so the boot will move before popping out.