Advection

"Transport of water or air along with its properties (e.g., temperature, chemical tracers) by the motion of the fluid. Regarding the general distinction between advection and convection, the former describes the predominantly horizontal, large-scale motions of the atmosphere or ocean, while convection describes the predominantly vertical, locally induced motions."

Convection is caused by the heating of water or air, causing it to rise - 'hot air rises'. So the movement is caused by the heating. In contrast Advection is movement that isn't caused by by the water or air that is being moved;the cause comes from outside such as the wind.

Definition based on (revised from) IPCC AR4.