An AHA (Alpha Hydroxy Acid) is a chemical exfoliant which works by peeling away the dead skin cells on the skin surface, revealing fresh new skin cells underneath. A BHA (Beta Hydroxy Acid) is also a gentle chemical exfoliant that works on the skin surface and inside the pores. BHAs work on a deeper level to clear trapped sebum in the pores and prevent new clogs from forming. AHAs and BHAs yield fuller skin when used together. This may be due to increased collagen production, which can make both the dermis and epidermis visibly plumper.