copiousness vs quantity

copiousness and quantity both are nouns.

Word	Noun	Adjective	Verb	Adverb
copiousness	Yes	No	No	No
quantity	Yes	No	No	No

As nouns, quantity is a hypernym of copiousness; that is, quantity is a word with a broader meaning than copiousness:

copiousness (noun)	quantity (noun)
the property of a more than adequate quantity or supply	how much there is or how many there are of something that you can quantify
	an adequate or large amount
	the concept that something has a magnitude and can be represented in mathematical expressions by a constant or a variable