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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 preformed vitamin A, found in animal products such as grass-fed meat and poultry, liver, fish, and raw organic dairy products like butter. 2  This is the form of vitamin A your body can actually use.