abundance vs quantity

abundance and quantity both are nouns.

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

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

abundance (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
(chemistry) the ratio of the total mass of an element in the earth's crust to the total mass of the earth's crust; expressed as a percentage or in parts per million	an adequate or large amount
(physics) the ratio of the number of atoms of a specific isotope of an element to the total number of isotopes present	the concept that something has a magnitude and can be represented in mathematical expressions by a constant or a variable