depletion vs drain

depletion and drain both are nouns.

Word	Noun	Adjective	Verb	Adverb
depletion	Yes	No	No	No
drain	Yes	No	Yes	No

As nouns, drain is a hyponym of depletion; that is, drain is a word with a more specific, narrower meaning than depletion:

Other hyponyms of depletion include consumption, expenditure, using up, exhaustion.

depletion (noun)	drain (noun)
the act of decreasing something markedly	emptying something accomplished by allowing liquid to run out of it
the state of being depleted	a gradual depletion of energy or resources
	a pipe through which liquid is carried away
	tube inserted into a body cavity (as during surgery) to remove unwanted material

depletion (verb)	drain (verb)
	empty of liquid; drain the liquid from
	make weak
	deplete of resources
	flow off gradually