caribou vs deer

caribou and deer both are nouns.

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

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

caribou: 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 caribou include cervid.

caribou (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