vitamin A vs vitamin A1

vitamin A and vitamin A1 both are nouns.

Word	Noun	Adjective	Verb	Adverb
vitamin A	Yes	No	No	No
vitamin A1	Yes	No	No	No

As nouns, vitamin A1 is a hyponym of vitamin A; that is, vitamin A1 is a word with a more specific, narrower meaning than vitamin A:

vitamin A: any of several fat-soluble vitamins essential for normal vision; prevents night blindness or inflammation or dryness of the eyes
vitamin A1: an unsaturated alcohol that occurs in marine fish-liver oils and is synthesized biologically from carotene

Other hyponyms of vitamin A include retinol, dehydroretinol, vitamin A2.

vitamin A (noun)	vitamin A1 (noun)
any of several fat-soluble vitamins essential for normal vision; prevents night blindness or inflammation or dryness of the eyes	an unsaturated alcohol that occurs in marine fish-liver oils and is synthesized biologically from carotene