As regards to Nigerian politics
Can a country practice two systems of government simultaneously ?
In my opinion,Nigeria practices two systems of government namely “Federal System of Government” and “Presidential System of Goverment”

Federal system of goverment is one in which governmental powers that exist in a country are shared between a central government that represents the whole country and governments of component region or states.

Presidential system of government is one in which all executive powers are vested in one person called the president and in which the executive arm of government is seperated from the legislature,but equal to it.

Going by the above definitions,Is my opinion about Nigeria practising two systems of government correct ?
Is there a difference between a federal system of government and a presidential system of government ?