eccentric vs crackpot

eccentric and crackpot both are nouns.

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

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

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

eccentric (noun)	crackpot (noun)
a person with an unusual or odd personality	a whimsically eccentric person
a person of a specified kind (usually with many eccentricities)

eccentric (adjective)	crackpot (adjective)
not having a common center; not concentric
conspicuously or grossly unconventional or unusual