Ulmus crassifolia vs elm

Ulmus crassifolia and elm both are nouns.

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

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

Ulmus crassifolia: elm of southern United States and Mexico having spreading pendulous corky branches
elm: any of various trees of the genus Ulmus: important timber or shade trees

Other hypernyms of Ulmus crassifolia include elm tree.

Ulmus crassifolia (noun)	elm (noun)
elm of southern United States and Mexico having spreading pendulous corky branches	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