nicotinic acid vs vitamin B

nicotinic acid and vitamin B both are nouns.

Word	Noun	Adjective	Verb	Adverb
nicotinic acid	Yes	No	No	No
vitamin B	Yes	No	No	No

As nouns, vitamin B is a hypernym of nicotinic acid; that is, vitamin B is a word with a broader meaning than nicotinic acid:

nicotinic acid: a B vitamin essential for the normal function of the nervous system and the gastrointestinal tract
vitamin B: originally thought to be a single vitamin but now separated into several B vitamins

Other hypernyms of nicotinic acid include B-complex vitamin, B, B complex, B vitamin, vitamin B complex.

nicotinic acid (noun)	vitamin B (noun)
a B vitamin essential for the normal function of the nervous system and the gastrointestinal tract	originally thought to be a single vitamin but now separated into several B vitamins