There is no difference in bitcoin and real money, bitcoin have both qualities , of real money and crypto currency. In fact bitcoin is better than the real money becasue holding of the real money can't generate income while the holding of the bitcoin does it. The rate of the income generation of bitcoin is very high than the real money. The Trade In bitcoin is also beneficial than real money. So bitcoin is better than the real money.
Bitcoin is not valid in most of the states in the world, cash is valid in every country. Cash is valid in every merchant, bitcoin is only valid in some merchants. Cash is very common but bitcoin is not, cash is legal.