start up vs crank

start up is not a noun while crank is a noun.

Word	Noun	Adjective	Verb	Adverb
start up	No	No	Yes	No
crank	Yes	Yes	Yes	No

As verbs, crank is a hyponym of start up; that is, crank is a word with a more specific, narrower meaning than start up:

Other hyponyms of start up include kick-start, hot-wire, re-start, restart, crank up, jump-start, jump, jumpstart.

start up (noun)	crank (noun)
	a hand tool consisting of a rotating shaft with parallel handle
	an amphetamine derivative (trade name Methedrine) used in the form of a crystalline hydrochloride; used as a stimulant to the nervous system and as an appetite suppressant
	a bad-tempered person
	a whimsically eccentric person

start up (adjective)	crank (adjective)
	(used of boats) inclined to heel over easily under sail