There are two fundamental differences between a cleanser and a makeup remover: their cosmetic formulation and their role in the beauty routine.
A makeup remover most often includes an oily phase, composed of lipid ingredients (fatty substances) which remove makeup particles, also of lipid origin.
A cleanser, meanwhile, contains surfactants, molecules which remove impurities from the face deposited by pollution, the urban environment.
If you wear makeup, even lightly, the makeup removal step is essential every evening. It allows you to remove the film of pigments applied in the morning. If you do not wear makeup, you can then proceed directly to cleansing.