As discussed in History of "Asian American" / "African American" nomenclature, the term African-American is a euphemism established to refer to Black Americans, but seems to be generally used to refer to those whose families have been in the United States for centuries (many of whose ancestors were originally brought to the U.S. as slaves).
More recently, there seems to have been a significant increase in immigration from Africa, and there are many new Americans from Africa who are somewhat culturally distinct from the "long-term" African-Americans described above.
Is there any existing terminology used to distinguish these two different groups?
No, we do not refer to English or British or Dutch Americans, nor to Danish or Swedish or half a dozen other ethnic groups.
We do refer to Irish or Italian or Polish Americans, among other ethnic groups.
Kenyan or Nigerian would clearly be much more specific than African but where did the distinction arise, please?
– Robbie Goodwin Jul 05 '18 at 21:30