ermine vs fur

ermine and fur both are nouns.

Word	Noun	Adjective	Verb	Adverb
ermine	Yes	No	No	No
fur	Yes	No	No	No

As nouns, fur is a hypernym of ermine; that is, fur is a word with a broader meaning than ermine:

Other hypernyms of ermine include pelt.

ermine (noun)	fur (noun)
mustelid of Northern Hemisphere in its white winter coat	dense coat of fine silky hairs on mammals (e.g., cat or seal or weasel)
the expensive white fur of the ermine	a garment made of animal pelts or synthetic fur
	the dressed hairy coat of a mammal