eccentric vs crank

eccentric and crank both are nouns.

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

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

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

eccentric (noun)	crank (noun)
a person with an unusual or odd personality	a hand tool consisting of a rotating shaft with parallel handle
a person of a specified kind (usually with many eccentricities)	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

eccentric (adjective)	crank (adjective)
not having a common center; not concentric	(used of boats) inclined to heel over easily under sail
conspicuously or grossly unconventional or unusual