Ulmus hollandica vs elm

Ulmus hollandica and elm both are nouns.

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

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

Ulmus hollandica: any of various hybrid ornamental European shade trees ranging from dwarf to tall
elm: any of various trees of the genus Ulmus: important timber or shade trees

Other hypernyms of Ulmus hollandica include elm tree.

Ulmus hollandica (noun)	elm (noun)
any of various hybrid ornamental European shade trees ranging from dwarf to tall	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