oatmeal cookie vs biscuit

oatmeal cookie and biscuit both are nouns.

Word	Noun	Adjective	Verb	Adverb
oatmeal cookie	Yes	No	No	No
biscuit	Yes	No	No	No

As nouns, biscuit is a hypernym of oatmeal cookie; that is, biscuit is a word with a broader meaning than oatmeal cookie:

Other hypernyms of oatmeal cookie include cookie, cooky.

oatmeal cookie (noun)	biscuit (noun)
cookies containing rolled oats	small round bread leavened with baking-powder or soda
	any of various small flat sweet cakes