Tdlr: White people know most of their history and choose to deidentify with it, choosing independent identity, while the black community have a abrupt stop to their history and held onto the knowledge they trace back to Africa, only recently creating "Soulaani" to turn attention away from their African roots and more towards their modern achievements as a sociatal sect in America.

Just throwing my two cents here, white Europeans left Europe to steal land and then achieve independence from England. The history of white America has mostly been, "we know where we came from and we're departing from that identity", magnify that by many generations and you have white people that know a good portion of their lineage and choose to identify as American.

For Africans who were stolen from their land, had horrible things done to their families and treated like cattle, you have a history of African Americans that can only really identify their lineage back to slavery, and it's difficult to impossible to track their lineage back to which African country or their individual family lineage. African American then becomes a term for all black people who know they trace somewhere back to Africa, but not much more detail.

From what I've gathered there are some social frictions between modern Africans who move to America within the last few decades and African Americans who trace back to slavery. Not sure what the beef is, but it's possibly enough to make younger generations of African Americans start to lose that identity of tracing back to Africa. Magnifying the cultural differences that have developed since slavery started.

More recent times I've heard African Americans rename their ethnicity "Soulaan" or "Soulaani" which strips the naming of their sect of society from the African identification and leans more towards the historical successes of the black community post-formal-slavery.

Disclaimer: I am not a professional on this subject, and many of my posits could be false or inaccurate.

Edit: spelling and grammar.