Corns and plantar warts are two different skin conditions, although both often occur on the feet, they have significant differences. First, corns and plantar warts differ in contagion and quantity. Generally, corns appear singly and are not contagious; while plantar warts often appear in larger numbers and are highly contagious. Moreover, corns are usually caused by pressure or friction on the feet, whereas plantar warts are caused by a viral infection of the skin on the soles of the feet.