Rangifer arcticus vs caribou

Rangifer arcticus and caribou both are nouns.

Word	Noun	Adjective	Verb	Adverb
Rangifer arcticus	Yes	No	No	No
caribou	Yes	No	No	No

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

Rangifer arcticus: of tundra of northern Canada; in some classifications included in the species Rangifer tarandus
caribou: Arctic deer with large antlers in both sexes; called `reindeer' in Eurasia and `caribou' in North America

Other hypernyms of Rangifer arcticus include Greenland caribou, Rangifer tarandus, reindeer.

Rangifer arcticus (noun)	caribou (noun)
of tundra of northern Canada; in some classifications included in the species Rangifer tarandus	Arctic deer with large antlers in both sexes; called `reindeer' in Eurasia and `caribou' in North America