Bound/rebound on a full size car is achieved in a completely different way. Full-size dampers will have adjustable valving which basically allows the damper to be "heavier" in compression and "lighter" in extension. There are a handful of RC shocks that have had this feature over the years (TTech predator with a flap, Thunder Tiger S3 with ball bearings), but the Tamiya shocks are not among them. In fact most of the cars that were released with two-way dampers ended up with having them replaced by simple pistons, clever pistons are slow to react and don't work on lightweight RC cars.

Rebound in a Tamiya-style shock is simply the spring effect of the bladder & air pocket. It affects both bound and rebound and whichever way you set it, all it does is affect the overall spring rate of the shock.