Shot blasting uses metal shot abrasives which are highly abrasive media. So it is typically used on metal surfaces which are harder to clean.For instance, remove rust and oxide scales or strip paint. 

Sandblasting uses gentler abrasives such as silica sand, organic media, glass or delicate metal. So it is typically used on more delicate materials such as plastic, aluminum, wood, stone, glass, or machinery with sensitive electrical components.

 

Second

During shot blasting, the medium is loaded into a centrifugal wheel which shoots the medium at the workpiece surface at high velocities. This is usually done in a closed chamber. 

Sandblasting relies on water or compressed air to fire the media at the workpiece surface at high speeds, though not as high as shot-blasting. 

Shot blasting


Sandblasting