provitamin vs carotene

provitamin and carotene both are nouns.

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

As nouns, carotene is a hyponym of provitamin; that is, carotene 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
carotene: an orange isomer of an unsaturated hydrocarbon found in many plants; is converted into vitamin A in the liver

Other hyponyms of provitamin include carotin, provitamin A.

provitamin (noun)	carotene (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
	yellow or orange-red fat-soluble pigments in plants