I'm not sure if black liberals are all that different from white liberals.
I don't think black liberals ideology wise are as "liberal". A decent amount have somewhat religious views too.
Many of the people you are talking about wouldn’t self identify as liberals, thus the comment above. The comparison would then not be apples to apples.
I’m not sure if there is much difference between self described liberals (or progressives) of different racial groups, although there certainly may be. Interested in seeing research.