Nuttall's oak vs oak tree

Nuttall's oak and oak tree both are nouns.

Word	Noun	Adjective	Verb	Adverb
Nuttall's oak	Yes	No	No	No
oak tree	Yes	No	No	No

As nouns, oak tree is a hypernym of Nuttall's oak; that is, oak tree is a word with a broader meaning than Nuttall's oak:

Nuttall's oak: similar to the pin oak; grows in damp sites in Mississippi River basin
oak tree: a deciduous tree of the genus Quercus; has acorns and lobed leaves

Other hypernyms of Nuttall's oak include oak.

Nuttall's oak (noun)	oak tree (noun)
similar to the pin oak; grows in damp sites in Mississippi River basin	a deciduous tree of the genus Quercus; has acorns and lobed leaves