Afro-American vs Black American

Afro-American and Black American both are nouns.

Word	Noun	Adjective	Verb	Adverb
Afro-American	Yes	Yes	No	No
Black American	Yes	No	No	No

As nouns, Afro-American and Black American are synonyms defined as:

Afro-American and Black American: an American whose ancestors were born in Africa

Other synonyms of Afro-American include African American.

Afro-American (noun)	Black American (noun)
an American whose ancestors were born in Africa	an American whose ancestors were born in Africa

Afro-American (adjective)	Black American (adjective)
pertaining to or characteristic of Americans of African ancestry