muster up vs rally

muster up is not a noun while rally is a noun.

Word	Noun	Adjective	Verb	Adverb
muster up	No	No	Yes	No
rally	Yes	No	Yes	No

As verbs, muster up and rally are synonyms defined as:

Other synonyms of muster up include come up, muster, summon.

muster up (noun)	rally (noun)
	(sports) an unbroken sequence of several successive strokes
	the feat of mustering strength for a renewed effort
	an automobile race run over public roads
	a large gathering of people intended to arouse enthusiasm
	a marked recovery of strength or spirits during an illness

muster up (verb)	rally (verb)
gather or bring together	return to a former condition
	harass with persistent criticism or carping
	call to arms; of military personnel
	gather
	gather or bring together