Whiteness studies is a variant of critical race theory, and thus of the Frankfurt School and Cultural Marxism more generally. It developed in the United States, particularly since the late 20th century, and many institutions in the United States and elsewhere now offer courses, giving influence and prestige to the anti-White ideology.
"Whiteness studies" is focused on "Whiteness" (Whites as a race) as a claimed social construct and vehemently criticizing Whites, including their history, culture, identity, achievements, "White privilege", supposed negative effects on non-Whites such as due to White colonialism, and so on.
There are many other "studies", such as Black studies, Chicano studies, Queer studies, women’s studies, and so on. However, unlike "Whiteness studies", these all aim to support, develop, and nurture the identities, agendas, and special interests of the studied group.
Another difference is that Black studies is not titled "Blackness studies".