drain vs eat up

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

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

As verbs, eat up is a hypernym of drain; that is, eat up is a word with a broader meaning than drain:

Other hypernyms of drain include consume, deplete, eat, exhaust, expend, run through, use, use up, wipe out.

drain (noun)	eat up (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

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