compost pile vs cumulus

compost pile and cumulus both are nouns.

Word	Noun	Adjective	Verb	Adverb
compost pile	Yes	No	No	No
cumulus	Yes	Yes	No	No

As nouns, cumulus is a hypernym of compost pile; that is, cumulus is a word with a broader meaning than compost pile:

compost pile: a heap of manure and vegetation and other organic residues that are decaying to become compost
cumulus: a collection of objects laid on top of each other

Other hypernyms of compost pile include agglomerate, cumulation, heap, mound, pile.

compost pile (noun)	cumulus (noun)
a heap of manure and vegetation and other organic residues that are decaying to become compost	a collection of objects laid on top of each other
	a globular cloud

compost pile (adjective)	cumulus (adjective)
	of or related to cumulous clouds