pep up vs urge

pep up is not a noun while urge is a noun.

Word	Noun	Adjective	Verb	Adverb
pep up	No	No	Yes	No
urge	Yes	No	Yes	No

As verbs, pep up and urge are synonyms defined as:

Other synonyms of pep up include barrack, cheer, exhort, inspire, root on, urge on.

pep up (noun)	urge (noun)
	a strong restless desire
	an instinctive motive

pep up (verb)	urge (verb)
make more interesting or lively	force or impel in an indicated direction
spur on or encourage especially by cheers and shouts	spur on or encourage especially by cheers and shouts
	push for something