geek vs crank

geek and crank both are nouns.

Word	Noun	Adjective	Verb	Adverb
geek	Yes	No	Yes	No
crank	Yes	Yes	Yes	No

As nouns, crank is a hyponym of geek; that is, crank is a word with a more specific, narrower meaning than geek:

Other hyponyms of geek include crackpot, fruitcake, nut, nut case, screwball, nutter, wacko, whacko.

geek (noun)	crank (noun)
a person with an unusual or odd personality	a hand tool consisting of a rotating shaft with parallel handle
a carnival performer who does disgusting acts	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

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