This seems to confuse a lot of people, so here's a quick explanation. Both shocks and struts serve the same purpose, to dampen the vibrations of a mechanical system. The difference is that a strut is an integral part of the suspension whereas a shock is just an add on damper. A strut supports the weight of the vehicle, and typically replaces the upper control arm and serves as pivots for the steering rack. A shock supports no significant weight and is installed soley to dampen the resonant vibrations of the spring.