Why do some people use the term "African-American" instead of Black, while still using the word "White"?

Updates
+1 y
And no "because people are sensitive/offended/blah blah blah" type of answers. Real factual answers only please
Updates
+1 y
The irony is that there is an organization called "Black Lives Matter" which is mainstreamized by many big name companies and yet MANY people still refuse to utter the word Black as if it was White
Why do some people use the term "African-American" instead of Black, while still using the word "White"?
Post Opinion