Sanders and grinders aren't the same. They are used in different work-related applications. Sanders are used in polishing, sanding and buffing applications, whereas grinders are used in cutting applications.

In addition to supporting different applications, sanders and grinders feature different parts. All sanders feature sandpaper or a sanding belt. Sandpaper and sanding belts are thin sheets of an abrasive material.

Grinders don't feature sandpaper, nor do they feature a sanding belt. Instead, grinders feature a cutting disc. The cutting disc is a wheel-shaped bladed tool. As it spins, it will cut into the object to which it's exposed. You can use a grinder to easily cut through objects, assuming the cutting disc isn't dull.

Both types of power tools support a variety of materials. Sanders are typically used with wooden objects, grinders are used with metal objects. If you need to cut through a metal object, you may want to use a grinder. To sand down a wooden workpiece so that it's smooth, you should use a sander.

Grinders are more versatile than sanders. You can use them in more applications. Sanders are limited to polishing, sanding and buffing applications. But grinders support all cutting-related applications.