This is a pretty good basic lesson in enzyme chemistry.
One misconception that I have been guilty of teaching is that they are bacteria. This article describes them as a “catalyst” for breaking down odor causing organic soils and stains.
Enzymes are created by bacteria. Some applications use live bacteria to create enzymes on the spot. Some formulations are pre created enzymes with the bacteria gone / dead.
The article also goes into some detail on the differences between types of enzymes targeting odors, and the (different formulations) targeting spots.
I’ve had pretty good results on both with a generic low cost product I buy from my Jan San house – but it could always be better.