Quercus kelloggii vs oak tree

Quercus kelloggii and oak tree both are nouns.

Word	Noun	Adjective	Verb	Adverb
Quercus kelloggii	Yes	No	No	No
oak tree	Yes	No	No	No

As nouns, oak tree is a hypernym of Quercus kelloggii; that is, oak tree is a word with a broader meaning than Quercus kelloggii:

Quercus kelloggii: large deciduous tree of the Pacific coast having deeply parted bristle-tipped leaves
oak tree: a deciduous tree of the genus Quercus; has acorns and lobed leaves

Other hypernyms of Quercus kelloggii include oak.

Quercus kelloggii (noun)	oak tree (noun)
large deciduous tree of the Pacific coast having deeply parted bristle-tipped leaves	a deciduous tree of the genus Quercus; has acorns and lobed leaves