Seville orange vs Citrus aurantium

Seville orange and Citrus aurantium both are nouns.

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

As nouns, Seville orange and Citrus aurantium are synonyms defined as:

Seville orange and Citrus aurantium: any of various common orange trees yielding sour or bitter fruit; used as grafting stock

Other synonyms of Seville orange include bigarade, bitter orange, bitter orange tree, marmalade orange, sour orange.

Seville orange (noun)	Citrus aurantium (noun)
highly acidic orange used especially in marmalade	any of various common orange trees yielding sour or bitter fruit; used as grafting stock
any of various common orange trees yielding sour or bitter fruit; used as grafting stock