niacin vs nicotinic acid

niacin and nicotinic acid both are nouns.

Word	Noun	Adjective	Verb	Adverb
niacin	Yes	No	No	No
nicotinic acid	Yes	No	No	No

As nouns, niacin and nicotinic acid are synonyms defined as:

niacin and nicotinic acid: a B vitamin essential for the normal function of the nervous system and the gastrointestinal tract

niacin (noun)	nicotinic acid (noun)
a B vitamin essential for the normal function of the nervous system and the gastrointestinal tract	a B vitamin essential for the normal function of the nervous system and the gastrointestinal tract