Peninsulares were Spaniards that came from Spain to live in Latin America. They were the lowest percentage of the population and were the only group allowed to hold political office.
Mulattos
Creoles were Spaniards who were born in Latin America. Unlike Peninsulares, they could not hold political office but could serve in the army. Creoles led the later Mexican revolutions and South American revolutions under Simón Bolívar and José de San Martín. Creoles spread Enlightenment ideas to other social classes.
Natives
Mestizos were essentially the middle class of Latin America. Mestizos had one Spanish parent and one Native parent. Mestizos were taught Enlightenment ideas by Creoles and led the early Mexican Revolution under Father Miguel Hidalgo.
Slaves
Mulattos were the lowest free class in Latin America. Mulattos had one Spanish parent and one Slave Parent (African).
Natives were people that were originally from Latin America before its takeover by Spain. They were originally used as slave labour. Spain eventually stopped using natives because they died off fast and frequently escaped due to their knowledge of the land.
Slaves were people shipped from Africa to supply labour on plantations among other gruelling work. Slaves led the Haitian Revolution under Toussaint L'Ouverture until his death in prison. The revolution they led was the only successful slave revolt in history.