white-tailed deer vs white tail

white-tailed deer and white tail both are nouns.

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

As nouns, white-tailed deer and white tail are synonyms defined as:

white-tailed deer and white tail: common North American deer; tail has a white underside

Other synonyms of white-tailed deer include Odocoileus Virginianus, Virginia deer, whitetail, whitetail deer.

white-tailed deer (noun)	white tail (noun)
common North American deer; tail has a white underside	common North American deer; tail has a white underside