bank bill vs paper money

bank bill and paper money both are nouns.

Word	Noun	Adjective	Verb	Adverb
bank bill	Yes	No	No	No
paper money	Yes	No	No	No

As nouns, paper money is a hypernym of bank bill; that is, paper money is a word with a broader meaning than bank bill:

bank bill: a piece of paper money (especially one issued by a central bank)
paper money: currency issued by a government or central bank and consisting of printed paper that can circulate as a substitute for specie

Other hypernyms of bank bill include folding money, paper currency.

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