How to Tell the Difference Between a Mole and a Freckle The Dermatology Specialists Freckles vs. Moles: Differences and Similarities Freckles develop when specific skin cells produce extra melanin in response to sunlight. When ultraviolet rays reach the skin, melanocytes release melanin to protect deeper layers from damage. In some people, certain Melanotan What It Is and Its Relation to Skin Cancer