Their is a lot difference between real money and Bitcoin. First of all bitcoin is an electronic money and real money is physical money. You can easily convert bitcoin to any other currency in any where but in case of real money it is quite difficult. Bitcoin is not a world convertible currency because some country it declared as a illegal but in case of real money this thing not happen. Bitcoin user doesn't pay tax  but in the case of real money you have to pay tax. When real money transaction occurs a third party must interrupted in the transition but bitcoin transaction doesn't need any third person involvment.