hierarch vs high priest

hierarch and high priest both are nouns.

Word	Noun	Adjective	Verb	Adverb
hierarch	Yes	No	No	No
high priest	Yes	No	No	No

As nouns, hierarch and high priest are synonyms defined as:

Other synonyms of hierarch include archpriest, prelate, primate.

hierarch (noun)	high priest (noun)
a senior clergyman and dignitary	a senior clergyman and dignitary
a person who holds a high position in a hierarchy	a preeminent authority or major proponent of a movement or doctrine