Arctic fox vs blue fox

Arctic fox and blue fox both are nouns.

Word	Noun	Adjective	Verb	Adverb
Arctic fox	Yes	No	No	No
blue fox	Yes	No	No	No

As nouns, blue fox is a hyponym of Arctic fox; that is, blue fox is a word with a more specific, narrower meaning than Arctic fox:

Arctic fox: thickly-furred fox of Arctic regions; brownish in summer and white in winter
blue fox: a variety of Arctic fox having a pale grey winter coat

Arctic fox (noun)	blue fox (noun)
thickly-furred fox of Arctic regions; brownish in summer and white in winter	a variety of Arctic fox having a pale grey winter coat