white tail vs deer

white tail and deer both are nouns.

Word	Noun	Adjective	Verb	Adverb
white tail	Yes	No	No	No
deer	Yes	No	No	No

As nouns, deer is a hypernym of white tail; that is, deer is a word with a broader meaning than white tail:

white tail: common North American deer; tail has a white underside
deer: distinguished from Bovidae by the male's having solid deciduous antlers

Other hypernyms of white tail include cervid.

white tail (noun)	deer (noun)
common North American deer; tail has a white underside	distinguished from Bovidae by the male's having solid deciduous antlers