American elk vs deer

American elk and deer both are nouns.

Word	Noun	Adjective	Verb	Adverb
American elk	Yes	No	No	No
deer	Yes	No	No	No

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

American elk: large North American deer with large much-branched antlers in the male
deer: distinguished from Bovidae by the male's having solid deciduous antlers

Other hypernyms of American elk include cervid.

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

American elk: common deer of temperate Europe and Asia
deer: distinguished from Bovidae by the male's having solid deciduous antlers

Other hypernyms of American elk include cervid.

American elk (noun)	deer (noun)
large North American deer with large much-branched antlers in the male	distinguished from Bovidae by the male's having solid deciduous antlers
common deer of temperate Europe and Asia