Citrus bergamia vs orange tree

Citrus bergamia and orange tree both are nouns.

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

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

Citrus bergamia: small tree with pear-shaped fruit whose oil is used in perfumery; Italy
orange tree: any citrus tree bearing oranges

Other hypernyms of Citrus bergamia include orange.

Citrus bergamia (noun)	orange tree (noun)
small tree with pear-shaped fruit whose oil is used in perfumery; Italy	any citrus tree bearing oranges