monk vs Cistercian

monk and Cistercian both are nouns.

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

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

monk: a male religious living in a cloister and devoting himself to contemplation and prayer and work
Cistercian: member of an order of monks noted for austerity and a vow of silence

Other hyponyms of monk include Brother, Carthusian, Trappist.

monk (noun)	Cistercian (noun)
a male religious living in a cloister and devoting himself to contemplation and prayer and work	member of an order of monks noted for austerity and a vow of silence