Scar is a collection of new connective tissue. In the skin scar implies damage to both epidermal and dermal layers. If there is more deposition of connective tissue(collagen), the scar is known as hypertrophic scar. These scars are initially red, raised, firm, and, at times, itchy and painful.
If the skin heals with the least amount of collagen, this is known as atrophic scar. Atrophic scars are shiny and papery thin to the touch.