provitamin vs carotin

provitamin and carotin both are nouns.

Word	Noun	Adjective	Verb	Adverb
provitamin	Yes	No	No	No
carotin	Yes	No	No	No

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

provitamin: vitamin precursor; a substance that is converted into a vitamin in animal tissues
carotin: an orange isomer of an unsaturated hydrocarbon found in many plants; is converted into vitamin A in the liver

Other hyponyms of provitamin include carotene, provitamin A.

provitamin (noun)	carotin (noun)
vitamin precursor; a substance that is converted into a vitamin in animal tissues	an orange isomer of an unsaturated hydrocarbon found in many plants; is converted into vitamin A in the liver