archpriest vs high priest

archpriest and high priest both are nouns.

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

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

Other synonyms of archpriest include hierarch, prelate, primate.

archpriest (noun)	high priest (noun)
a senior clergyman and dignitary	a senior clergyman and dignitary
	a preeminent authority or major proponent of a movement or doctrine