postulator vs clergyman

postulator and clergyman both are nouns.

Word	Noun	Adjective	Verb	Adverb
postulator	Yes	No	No	No
clergyman	Yes	No	No	No

As nouns, clergyman is a hypernym of postulator; that is, clergyman is a word with a broader meaning than postulator:

postulator: (Roman Catholic Church) someone who proposes or pleads for a candidate for beatification or canonization
clergyman: a member of the clergy and a spiritual leader of the Christian Church

Other hypernyms of postulator include man of the cloth, reverend.

postulator (noun)	clergyman (noun)
someone who assumes or takes something for granted as the basis of an argument	a member of the clergy and a spiritual leader of the Christian Church
(Roman Catholic Church) someone who proposes or pleads for a candidate for beatification or canonization