peacekeeper vs guardian

peacekeeper and guardian both are nouns.

Word	Noun	Adjective	Verb	Adverb
peacekeeper	Yes	No	No	No
guardian	Yes	No	No	No

As nouns, guardian is a hypernym of peacekeeper; that is, guardian is a word with a broader meaning than peacekeeper:

Other hypernyms of peacekeeper include defender, protector, shielder.

peacekeeper (noun)	guardian (noun)
the pistol of a law officer in the old West	a person who cares for persons or property
someone who keeps peace
a member of a military force that is assigned (often with international sanction) to preserve peace in a trouble area