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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.
Retin-A is a brand name for the ingredient tretinoin, part of a family of related products known as retinoids, which derms consider to be the gold standard ingredient in anti-aging topicals. Retin-A is sold at the pharmacy under other brand names like Micro, Renova, Avage and Tazorac. Its less potent over-the-counter form, retinol, which is considered to be Retin-Aâs little sister, is found in products on department and drugstore shelves.