Ulmus rubra vs elm

Ulmus rubra and elm both are nouns.

Word	Noun	Adjective	Verb	Adverb
Ulmus rubra	Yes	No	No	No
elm	Yes	No	No	No

As nouns, elm is a hypernym of Ulmus rubra; that is, elm is a word with a broader meaning than Ulmus rubra:

Ulmus rubra: North American elm having rough leaves that are red when opening; yields a hard wood
elm: any of various trees of the genus Ulmus: important timber or shade trees

Other hypernyms of Ulmus rubra include elm tree.

Ulmus rubra (noun)	elm (noun)
North American elm having rough leaves that are red when opening; yields a hard wood	any of various trees of the genus Ulmus: important timber or shade trees
	hard tough wood of an elm tree; used for e.g. implements and furniture