the point, simply, is that there is a difference between Black as a race and Black as a culture
Black as a culture (or perhaps as a nationality want more specificity finer) speaks to the specific cumulative language, art, and influence of Black people in America. Different. for example, than Ethiopian or Jamaican. It is a *collection* of all the experiences we have which has resulted in our input into the larger American culture
Black as a race speaks more toward whether or not you trace back primarily to African blood (as opposed to Asian or whatever)
it ain't that deep, and doesn't have to be ground into a fine powder for validity