vitamin A2 vs vitamin A

vitamin A2 and vitamin A both are nouns.

Word	Noun	Adjective	Verb	Adverb
vitamin A2	Yes	No	No	No
vitamin A	Yes	No	No	No

As nouns, vitamin A is a hypernym of vitamin A2; that is, vitamin A is a word with a broader meaning than vitamin A2:

vitamin A2: a viscous alcohol that is less active in mammals than is vitamin A1
vitamin A: any of several fat-soluble vitamins essential for normal vision; prevents night blindness or inflammation or dryness of the eyes

Other hypernyms of vitamin A2 include A, antiophthalmic factor, axerophthol.

vitamin A2 (noun)	vitamin A (noun)
a viscous alcohol that is less active in mammals than is vitamin A1	any of several fat-soluble vitamins essential for normal vision; prevents night blindness or inflammation or dryness of the eyes