northern pin oak vs oak tree

northern pin oak and oak tree both are nouns.

Word	Noun	Adjective	Verb	Adverb
northern pin oak	Yes	No	No	No
oak tree	Yes	No	No	No

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

northern pin oak: small to medium deciduous oak of east central North America; leaves have sharply pointed lobes
oak tree: a deciduous tree of the genus Quercus; has acorns and lobed leaves

Other hypernyms of northern pin oak include oak.

northern pin oak (noun)	oak tree (noun)
small to medium deciduous oak of east central North America; leaves have sharply pointed lobes	a deciduous tree of the genus Quercus; has acorns and lobed leaves