spank vs beat up

spank is a noun but beat up is not a noun.

Word	Noun	Adjective	Verb	Adverb
spank	Yes	No	Yes	No
beat up	No	No	Yes	No

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

spank: give a spanking to; subject to a spanking
beat up: give a beating to; subject to a beating, either as a punishment or as an act of aggression

Other hypernyms of spank include beat, work over.

spank (noun)	beat up (noun)
a slap with the flat of the hand

spank (verb)	beat up (verb)
give a spanking to; subject to a spanking	gather
	give a beating to; subject to a beating, either as a punishment or as an act of aggression