They are actually all money but the big difference is Bitcoin the users are few while money we all use it. In the current situation only money is legal while bitcoin is not legal in some countries, so basically you can see that bitcoin is weaker compared to real money.
but i do not think so, have less user is not the characteristic of bitcoin, to me the big difference is that bitcoin is decentralize currency while real currency is centralized currency, bitcoin is online crypto currency, while fiat is real paper money.