What characteristics they have make them better for certain type of riding.
No one seems to have addressed this question yet, so:
Most people (doesn't have to mean you, of course) prefer more flexible bindings for park riding, stiffer bindings for freeriding, and something in the middle for all-mountain riding. The parts of the binding to which the flexible/stiff rating applies the most are the highback and the ankle strap, although the entire chassis can be more or less rigid, I suppose.
Another performance factor is ease of entry, especially if you are riding park or freeriding at a small resort with short runs. Rear-entry bindings (e.g., Flows, some K2's) or single-ratchet bindings (e.g., Ride Contrabands) can reduce the time you spend fussing with bindings after you get off the lift.