critic vs reviewer

critic and reviewer both are nouns.

Word	Noun	Adjective	Verb	Adverb
critic	Yes	No	No	No
reviewer	Yes	No	No	No

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

critic: anyone who expresses a reasoned judgment of something
reviewer: someone who reads manuscripts and judges their suitability for publication

critic (noun)	reviewer (noun)
a person who is professionally engaged in the analysis and interpretation of works of art	a writer who reports and analyzes events of the day
anyone who expresses a reasoned judgment of something	someone who reads manuscripts and judges their suitability for publication
someone who frequently finds fault or makes harsh and unfair judgments