lots vs stacks

lots and stacks both are nouns.

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

As nouns, lots and stacks are synonyms defined as:

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

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

lots (adverb)	stacks (adverb)
to a very great degree or extent