Pinus serotina vs pine tree

Pinus serotina and pine tree both are nouns.

Word	Noun	Adjective	Verb	Adverb
Pinus serotina	Yes	No	No	No
pine tree	Yes	No	No	No

As nouns, pine tree is a hypernym of Pinus serotina; that is, pine tree is a word with a broader meaning than Pinus serotina:

Pinus serotina: large three-needled pine of sandy swamps of southeastern United States; needles longer than those of the northern pitch pine
pine tree: a coniferous tree

Other hypernyms of Pinus serotina include pine, true pine.

Pinus serotina (noun)	pine tree (noun)
large three-needled pine of sandy swamps of southeastern United States; needles longer than those of the northern pitch pine	a coniferous tree