provitamin A vs provitamin

provitamin A and provitamin both are nouns.

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

As nouns, provitamin is a hypernym of provitamin A; that is, provitamin is a word with a broader meaning than provitamin A:

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

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