reindeer vs deer

reindeer and deer both are nouns.

Word	Noun	Adjective	Verb	Adverb
reindeer	Yes	No	No	No
deer	Yes	No	No	No

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

reindeer: Arctic deer with large antlers in both sexes; called `reindeer' in Eurasia and `caribou' in North America
deer: distinguished from Bovidae by the male's having solid deciduous antlers

Other hypernyms of reindeer include cervid.

reindeer (noun)	deer (noun)
Arctic deer with large antlers in both sexes; called `reindeer' in Eurasia and `caribou' in North America	distinguished from Bovidae by the male's having solid deciduous antlers