greenback vs banker's bill

greenback and banker's bill both are nouns.

Word	Noun	Adjective	Verb	Adverb
greenback	Yes	No	No	No
banker's bill	Yes	No	No	No

As nouns, greenback and banker's bill are synonyms defined as:

greenback and banker's bill: a piece of paper money (especially one issued by a central bank)

Other synonyms of greenback include bank bill, bank note, banknote, bill, Federal Reserve note, government note, note.

greenback (noun)	banker's bill (noun)
a piece of paper money (especially one issued by a central bank)	a piece of paper money (especially one issued by a central bank)