[research] How do bleaching creams know the difference between hyperpigmentation and your natural skin tone?

Beauty Tips For Body Care
What is the difference between pigmentation acquired due to inflammation vs your natural skin tone? Why do hyperpigmentation products only work on hyperpigmentation and not on your natural skin tone? I thought that the melanin cells are the same. Please note that I am only asking this question out of curiosity and I don’t believe in lightening natural skin color.
Girls Blog 2015
Submitted by StatisticianNext9384