A die grinder is a handheld power tool that is used for grinding, sanding, and polishing. Die grinders are very versatile and can be used on a variety of materials, including metal, plastic, and wood. Die grinders are available in both electric and pneumatic versions. The Dremel is a brand of rotary tool that is very similar to a die grinder. Both tools are handheld and can be used for the same applications. However, the Dremel is powered by electricity while the die grinder can be powered by either electricity or compressed air.