stacks vs tons

stacks and tons both are nouns.

Word	Noun	Adjective	Verb	Adverb
stacks	Yes	No	No	No
tons	Yes	No	No	No

As nouns, stacks and tons are synonyms defined as:

Other synonyms of stacks include dozens, gobs, heaps, lashings, loads, lots, oodles, piles, rafts, scads, scores, slews, wads.

stacks (noun)	tons (noun)
storage space in a library consisting of an extensive arrangement of bookshelves where most of the books are stored	a large number or amount
a large number or amount