Picture of Corns and Calluses
A corn is a thickened overgrowth of dead skin that usually appears on the tops or the sides of toes. A corn may be soft or hard. Some corns appear on the bottom of the feet. Corns here may develop due to blocked sweat glands.
Calluses are thickened patches of skin that may develop on skin areas experiencing friction, like the hands or feet. Calluses that form on the bottom of the feet are called plantar calluses.
Text Reference: American Podiatric Medical Association: "Corns and Calluses"