Convex and concave lenses differ in shape and light behavior. A convex lens bulges outward and converges light rays to a focal point, useful in magnifying glasses and cameras. In contrast, a concave lens curves inward, dispersing incoming light rays without focusing. It is beneficial for correcting vision problems like nearsightedness and in devices like corrective eyeglasses. Their shapes and how they handle light determine their distinct functions in various optical applications.