A deodorant keeps you fresh by counteracting body odor, but it doesn't reduce the amount of sweat on your skin. If you want to control sweat, you need an antiperspirant.
Antiperspirants usually contain aluminum, which blocks the sweat ducts in order to reduce the amount of sweat that reaches the surface of the skin. Antiperspirants are also deodorants, in the sense that they also have components that counteract body odor, but their main function is to keep sweat in check and help you avoid underarm wetness.