fullerene vs buckyball

fullerene and buckyball both are nouns.

Word	Noun	Adjective	Verb	Adverb
fullerene	Yes	No	No	No
buckyball	Yes	No	No	No

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

fullerene: a form of carbon having a large molecule consisting of an empty cage of sixty or more carbon atoms
buckyball: a spheroidal fullerene; the first known example of a fullerene

Other hyponyms of fullerene include buckminsterfullerene, carbon nanotube, nanotube.

fullerene (noun)	buckyball (noun)
a form of carbon having a large molecule consisting of an empty cage of sixty or more carbon atoms	a spheroidal fullerene; the first known example of a fullerene