You've probably heard about Alpha Hydroxy Acid (AHA) or Beta Hydroxy Acid (BHA) chemical exfoliants. These are typically what people think of when they hear 'chemical exfoliant'. But there's another type - an enzymatic or enzyme exfoliant.
Think of them as your chemical exfoliant's timid half-sibling; they both kind of work in adjacent ways, but they're not exactly the same thing.
Despite often being classed as a chemical exfoliant, enzymes don't technically count as chemical because they are biological molecules. However, like their chemical counterparts, enzymatic products exfoliate the skin (albeit much gently) and can have positive effects on acne and wrinkles–a trait attributed to the antioxidant properties seen in some extracts.
With that in mind, there are a few key differences in the mechanisms by which they work. Chemical exfoliants like glycolic or salicylic acid promote skin cell turnover by dissolving the intracellular 'glue' that holds your superficial skin cells together.
Enzyme exfoliants, on the other hand, contain proteolytic enzymes: this basically means that they break down proteins. Specifically, they break down the keratin protein that binds the Stratum corneum of the epidermis (the rough, dull most superficial layer of your skin).
The enzymes, the tiny molecules that are found in fruits, literally digest the dead skin on your face. You may have heard people talk about how pineapple gives you a tingling feeling in the mouth because it's eating you back. It's a similar principle here.
Since enzymes will only digest the dead skin cells, it won't over exfoliate your complexion like other products could. This means that anyone with sensitive skin can benefit from using one of these. It's exfoliation but on a much gentler level.