AT bindings differ from their alpine counterparts in that they aren't meant only for skiing downhill. Instead they allow the skier to free the heel of the boot, while staying clipped in at the toe, which creates the ability to “walk” naturally uphill on skis.

Do at boots work in alpine bindings?

MOST AT boots and alpine boots will work with MOST frame AT bindings (Marker, Salomon/Atomic, Tyrolia, Fritschi), but be sure to check the manufacturer's recommendations. ... AT boots with rockered ISO 9523 Touring soles are not compatible with many Alpine bindings. Even if they "fit", release may not be consistent.

What is an AT binding?

Alpine touring bindings (also known as "AT bindings" or "Randonnée bindings" if you're feeling continental) allow you to lift your heels naturally while skinning uphill, then lock your boots down and use regular alpine skiing technique when you want to go downhill.