Black Friar vs friar

Black Friar and friar both are nouns.

Word	Noun	Adjective	Verb	Adverb
Black Friar	Yes	No	No	No
friar	Yes	No	No	No

As nouns, friar is a hypernym of Black Friar; that is, friar is a word with a broader meaning than Black Friar:

Black Friar: a Roman Catholic friar wearing the black mantle of the Dominican order
friar: a male member of a religious order that originally relied solely on alms

Other hypernyms of Black Friar include mendicant.

Black Friar (noun)	friar (noun)
a Roman Catholic friar wearing the black mantle of the Dominican order	a male member of a religious order that originally relied solely on alms