tannic acid vs catechin

tannic acid and catechin both are nouns.

Word	Noun	Adjective	Verb	Adverb
tannic acid	Yes	No	No	No
catechin	Yes	No	No	No

As nouns, catechin is a hyponym of tannic acid; that is, catechin is a word with a more specific, narrower meaning than tannic acid:

tannic acid: any of various complex phenolic substances of plant origin; used in tanning and in medicine
catechin: a tannic acid that is extracted from black catechu as a white crystalline substance

Other hyponyms of tannic acid include cutch, kutch.

tannic acid (noun)	catechin (noun)
any of various complex phenolic substances of plant origin; used in tanning and in medicine	a tannic acid that is extracted from black catechu as a white crystalline substance