high priest vs priest

high priest and priest both are nouns.

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

As nouns, priest is a hypernym of high priest; that is, priest is a word with a broader meaning than high priest:

high priest: a senior clergyman and dignitary
priest: a clergyman in Christian churches who has the authority to perform or administer various religious rites; one of the Holy Orders

high priest (noun)	priest (noun)
a senior clergyman and dignitary	a clergyman in Christian churches who has the authority to perform or administer various religious rites; one of the Holy Orders
a preeminent authority or major proponent of a movement or doctrine	a person who performs religious duties and ceremonies in a non-Christian religion