bitter orange vs Seville orange

bitter orange and Seville orange both are nouns.

Word	Noun	Adjective	Verb	Adverb
bitter orange	Yes	No	No	No
Seville orange	Yes	No	No	No

As nouns, bitter orange and Seville orange are synonyms defined as:

bitter orange and Seville orange: highly acidic orange used especially in marmalade

Other synonyms of bitter orange include sour orange.

As nouns, bitter orange and Seville orange are synonyms defined as:

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

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

bitter orange (noun)	Seville orange (noun)
highly acidic orange used especially in marmalade	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