No pepper spray is exactly what it sounds like, pepper spray, IDR what pepper is used exactly but it uses the chimicles in the pepper to cause an irritation to the eyes.
Mace is a man made chimical that not only burns the eyes but the skin as well.
Its considered a chimical weapon and IIRC is why its not legal for a civilian outside of law enforcement/civil service to have on them
Pepper spray doesnt bother some people, which is why cops use mace.