eat up vs drain

eat up is not a noun while drain is a noun.

Word	Noun	Adjective	Verb	Adverb
eat up	No	No	Yes	No
drain	Yes	No	Yes	No

As verbs, drain is a hyponym of eat up; that is, drain is a word with a more specific, narrower meaning than eat up:

eat up (noun)	drain (noun)
	emptying something accomplished by allowing liquid to run out of it
	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

eat up (verb)	drain (verb)
finish eating all the food on one's plate or on the table	empty of liquid; drain the liquid from
use up (resources or materials)	make weak
enclose or envelop completely, as if by swallowing	deplete of resources
	flow off gradually