greenback vs government note

greenback and government note both are nouns.

Word	Noun	Adjective	Verb	Adverb
greenback	Yes	No	No	No
government note	Yes	No	No	No

As nouns, greenback and government note are synonyms defined as:

greenback and government note: a piece of paper money (especially one issued by a central bank)

Other synonyms of greenback include bank bill, bank note, banker's bill, banknote, bill, Federal Reserve note, note.

greenback (noun)	government note (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)