evaluator vs appraiser

evaluator and appraiser both are nouns.

Word	Noun	Adjective	Verb	Adverb
evaluator	Yes	No	No	No
appraiser	Yes	No	No	No

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

evaluator: an authority who is able to estimate worth or quality
appraiser: one who estimates officially the worth or value or quality of things

Other hyponyms of evaluator include valuator, arbiter, arbitrator, umpire, critic.

evaluator (noun)	appraiser (noun)
an authority who is able to estimate worth or quality	one who estimates officially the worth or value or quality of things
	one who determines authenticity (as of works of art) or who guarantees validity