HUGE. Ringworm is a skin infection spread from a person or a cat. The source is usually a kitten. Typically it is scaley with a clearing in the center, slightly itchy, and slowly spreading. Impetigo spreads rapidly, usually the lower face, with honey-colored crusts and maybe blisters. The skin is puffy & sore. Impetigo is transmitted from another person, an infection by strep or staph bacteria.
Impetigo = bacterial. Ringworm (tinea corporis) is a fungal infection and can spread to other parts of the body or to other people. Treatment is usually with over-the-counter anti-fungal creams (lotrimin (clotrimazole) af). Rashes that don't go away easily, or those that keep returning after treatment, should be evaluated by a doctor. People with diabetes get more fungal infections, and have a harder time getting rid of infections.