religious vs monk

religious and monk both are nouns.

Word	Noun	Adjective	Verb	Adverb
religious	Yes	Yes	No	No
monk	Yes	No	No	No

As nouns, monk is a hyponym of religious; that is, monk is a word with a more specific, narrower meaning than religious:

religious: a member of a religious order who is bound by vows of poverty and chastity and obedience
monk: a male religious living in a cloister and devoting himself to contemplation and prayer and work

Other hyponyms of religious include friar, mendicant, monastic, Benedictine, Jesuit, nun, eremite, cenobite, coenobite, superior, votary.

religious (noun)	monk (noun)
a member of a religious order who is bound by vows of poverty and chastity and obedience	a male religious living in a cloister and devoting himself to contemplation and prayer and work

religious (adjective)	monk (adjective)
having or showing belief in and reverence for a deity
of or relating to clergy bound by monastic vows
concerned with sacred matters or religion or the church
extremely scrupulous and conscientious