Alnus rhombifolia vs alder tree

Alnus rhombifolia and alder tree both are nouns.

Word	Noun	Adjective	Verb	Adverb
Alnus rhombifolia	Yes	No	No	No
alder tree	Yes	No	No	No

As nouns, alder tree is a hypernym of Alnus rhombifolia; that is, alder tree is a word with a broader meaning than Alnus rhombifolia:

Alnus rhombifolia: tree of western United States
alder tree: north temperate shrubs or trees having toothed leaves and conelike fruit; bark is used in tanning and dyeing and the wood is rot-resistant

Other hypernyms of Alnus rhombifolia include alder.

Alnus rhombifolia (noun)	alder tree (noun)
tree of western United States	north temperate shrubs or trees having toothed leaves and conelike fruit; bark is used in tanning and dyeing and the wood is rot-resistant