In a unitary system of government, the power of government is allocated to only one unit. In other words, there is only one central system of government in a unitary system of government.
In a federal system of government, the power of government is shared into different governing bodies -the local and national bodies, all of which relay information to those at the national helm of affairs.
In a unitary system of government, all the different states are governed by one ruler.
In a federal system of government, all the states are sovereign and granted the liberty to be self-ruled.