piles vs dozens

piles and dozens both are nouns.

Word	Noun	Adjective	Verb	Adverb
piles	Yes	No	No	No
dozens	Yes	No	No	No

As nouns, piles and dozens are synonyms defined as:

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

piles (noun)	dozens (noun)
a large number or amount	a large number or amount
venous swelling external or internal to the anal sphincter