welt vs beat up

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

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

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

welt: beat severely with a whip or rod
beat up: give a beating to; subject to a beating, either as a punishment or as an act of aggression

Other hypernyms of welt include beat, work over.

welt (noun)	beat up (noun)
a raised or strengthened seam
a raised mark on the skin (as produced by the blow of a whip); characteristic of many allergic reactions

welt (verb)	beat up (verb)
put a welt on	gather
beat severely with a whip or rod	give a beating to; subject to a beating, either as a punishment or as an act of aggression