There are two common types of grinders which are used to grind coffee in the U.S. They are the coffee mill and the coffee grinder. The coffee mill flakes the coffee bean while the coffee grinder chops the beans in the same way a blender chops food.
Coffee Mill: The coffee mill uses a steel plate or burrs to flake the coffee beans into ground coffee. Most mills are adjustable and can be adjusted for a coarse or fine grind. The mill is the best way to grind the coffee and insure that the coffee grind is uniform.
Coffee Grinder: The coffee "blade grinder" uses two steel blades that are powered by an electric motor. The blades whirl in a circular motion and chops the bean again and again until you stop grinding. The type of grind is determined by how long you leave the grinder on. It is very difficult to get an even grind with the blade grinder.