Epiduo and retrieve which one is better?

Hard to tell: Epiduo is a combination of Adapalene (the drug in differin (adapalene)) and benzoyl peroxide (a common over-the-counter acne drug). Retrieve is tretinoin (the drug in retin-a), so it would be similar to differin (adapalene). So, epiduo may have an advantage in that it includes benzoyl peroxide, which has some bacterial-killing ability. One can try one drug on the left face, and the other on the right face, to compare.