As someone who's tried both prescription and over-the-counter azelaic acid products, I've noticed a few key differences between the two. First, prescription azelaic acid typically has a higher concentration, making it more potent than its over-the-counter counterparts. Second, the over-the-counter options tend to be more affordable and easily accessible, while prescription products require a visit to the doctor. Third, prescription azelaic acid may be combined with other active ingredients, making it more effective for specific skin concerns. Lastly, some people might experience stronger side effects with prescription azelaic acid due to its higher concentration.