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The two are often believed to be interchangeable, but the main difference is that retinol is eventually converted into retinoic acid. Retinol is a natural form of vitamin A, while Retin-A is derived from retinoic acid, a synthetic derivative of vitamin A, and considered pharmaceutical.
Retinoic acid is the active form of vitamin A in the skin and the gold standard in anti-aging skin care, according to Burke. Topical retinoic acid (brand names Renova and Retin-A) treats fine wrinkles, age spots, and rough skin caused by sun exposure.