The three are often lumped together, but in fact have very different implications. At universities, considering race as one among many factors when admitting students. In government contracting, setting aside a percentage of business for firms owned by minorities or women. At the center of the debate are preferences. Preferences discriminate against the people who don't get them, mostly white males, and they are not true to American ideals of individual merit and equal opportunity.
Discrimination is still widespread, and overcoming it is still an urgent goal of public policy.
Preferences, when they exist at all, are one small part of the broader policy. Preferences, after all, are all around us. In college admissions, for example, preferences are given to athletes and children of alumni. In certain jobs, veterans get preferences. In many occupations, knowing someone at the top will result in a candidate being preferred.