[whats_a_quasar]

Protected categories = you can't refuse to hire someone because they're not white

Affirmative action = you can give someone an advantage in a hiring process because they're not white, with the intention of correcting historical discrimination

They are closely related in that they deal with race, gender, and class distinctions. But the ethics of the two are quite different. Banning discrimination by protected categories is uncontroversial. People have a lot more disagreements about affirmative action.