bitter orange vs sour orange

bitter orange and sour orange both are nouns.

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

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

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

Other synonyms of bitter orange include Seville orange.

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

bitter orange and sour 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, Seville orange.

bitter orange (noun)	sour 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