Citrus aurantium vs orange tree

Citrus aurantium and orange tree both are nouns.

Word	Noun	Adjective	Verb	Adverb
Citrus aurantium	Yes	No	No	No
orange tree	Yes	No	No	No

As nouns, orange tree is a hypernym of Citrus aurantium; that is, orange tree is a word with a broader meaning than Citrus aurantium:

Citrus aurantium: any of various common orange trees yielding sour or bitter fruit; used as grafting stock
orange tree: any citrus tree bearing oranges

Other hypernyms of Citrus aurantium include orange.

Citrus aurantium (noun)	orange tree (noun)
any of various common orange trees yielding sour or bitter fruit; used as grafting stock	any citrus tree bearing oranges