paper money vs paper currency

paper money and paper currency both are nouns.

Word	Noun	Adjective	Verb	Adverb
paper money	Yes	No	No	No
paper currency	Yes	No	No	No

As nouns, paper money and paper currency are synonyms defined as:

paper money and paper currency: currency issued by a government or central bank and consisting of printed paper that can circulate as a substitute for specie

Other synonyms of paper money include folding money.

paper money (noun)	paper currency (noun)
currency issued by a government or central bank and consisting of printed paper that can circulate as a substitute for specie	currency issued by a government or central bank and consisting of printed paper that can circulate as a substitute for specie