indefinite quantity vs amount

indefinite quantity and amount both are nouns.

Word	Noun	Adjective	Verb	Adverb
indefinite quantity	Yes	No	No	No
amount	Yes	No	Yes	No

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

indefinite quantity: an estimated quantity
amount: how much there is or how many there are of something that you can quantify

Other hypernyms of indefinite quantity include measure, quantity.

indefinite quantity (noun)	amount (noun)
an estimated quantity	how much there is or how many there are of something that you can quantify
	the relative magnitude of something with reference to a criterion
	a quantity obtained by the addition of a group of numbers
	a quantity of money

indefinite quantity (verb)	amount (verb)
	to measure up to in kind or quality
	add up in number or quantity
	be tantamount or equivalent to