I’m not black so obviously I don’t have best understanding of cultural history but I’m pretty sure “black power” was a term coined during the civil rights era for African Americans fighting for equal rights. “White power” is the term white nationalists/supremacists use to promote racist ideals which stemmed from the kkk and other white supremacist groups in order to suppress civil rights. Black lives matter isn’t really the same thing as black power as its used for a specific cause of police brutality/prejudice whether it be attempting to improve police/inner city relations in some cases or to speak out against racist laws such as “stop and frisk”