both are currency and has value and can be used as a medium of exchange. bitcoin can be likened into a cheque which has the value that can stand to purchase item but may not be generally acceptable. that is it. bitcoin cannot directly be used for petty trading but money can be used.
Don't get the wrong idea get some facts instead being a medium of exchange itself is a primary feature of a money therefore both currency can be considered as money. You are referring to fiat which is a paper bills or coins and not money itself. Considering the definition of money both Fiat and Crypto are qualified having different categories
of having physical preference is not applicable with crypto/bitcoin, but the usage can act simultaneously.