critic vs art critic

critic and art critic both are nouns.

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

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

critic: a person who is professionally engaged in the analysis and interpretation of works of art
art critic: a critic of paintings

Other hyponyms of critic include drama critic, theater critic, literary critic, music critic, newspaper critic.

critic (noun)	art critic (noun)
a person who is professionally engaged in the analysis and interpretation of works of art	a critic of paintings
anyone who expresses a reasoned judgment of something
someone who frequently finds fault or makes harsh and unfair judgments