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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.
1 Retinol is a cosmetic ingredient that any cosmetics company can include in its products. 2  It does not require a prescription. 3  Other effective forms of cosmetic-grade vitamin A that you'll see in cosmetics include retinyl acetate, retinyl palmitate, and retinaldehyde, among others.