small indefinite quantity vs small indefinite amount

small indefinite quantity and small indefinite amount both are nouns.

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

As nouns, small indefinite quantity and small indefinite amount are synonyms defined as:

small indefinite quantity and small indefinite amount: an indefinite quantity that is below average size or magnitude

small indefinite quantity (noun)	small indefinite amount (noun)
an indefinite quantity that is below average size or magnitude	an indefinite quantity that is below average size or magnitude