APCs are fundamentally different from tanks. Generally speaking, APCs have lighter armor (still strong enough to resist bullets and shrapnel) compared to tanks. They have lighter armament because of their focused transport purpose and for the sake of mobility. Most commonly, APCs are armed with machine guns or automatic grenade launchers. It can either have wheels or caterpillar tracks, while tanks are always tracked. Some can be amphibious.
Not only the military, police tactical units also operate it. Sometimes APCs can be utilized as ambulance, especially in battlefield (see post #1085064).
