carotenoid vs antioxidant

carotenoid and antioxidant both are nouns.

Word	Noun	Adjective	Verb	Adverb
carotenoid	Yes	No	No	No
antioxidant	Yes	No	No	No

As nouns, antioxidant is a hypernym of carotenoid; that is, antioxidant is a word with a broader meaning than carotenoid:

carotenoid: any of a class of highly unsaturated yellow to red pigments occurring in plants and animals
antioxidant: substance that inhibits oxidation or inhibits reactions promoted by oxygen or peroxides

Other hypernyms of carotenoid include phytochemical, pigment.

carotenoid (noun)	antioxidant (noun)
any of a class of highly unsaturated yellow to red pigments occurring in plants and animals	substance that inhibits oxidation or inhibits reactions promoted by oxygen or peroxides