Quercus laevis vs oak tree

Quercus laevis and oak tree both are nouns.

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

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

Quercus laevis: small slow-growing deciduous shrubby tree of dry sandy barrens of southeastern United States having leaves with bristle-tipped lobes resembling turkey's toes
oak tree: a deciduous tree of the genus Quercus; has acorns and lobed leaves

Other hypernyms of Quercus laevis include oak.

Quercus laevis (noun)	oak tree (noun)
small slow-growing deciduous shrubby tree of dry sandy barrens of southeastern United States having leaves with bristle-tipped lobes resembling turkey's toes	a deciduous tree of the genus Quercus; has acorns and lobed leaves