How does a federal system of government compare to the unitary system?

In a federal
government, governmental power is split between a national, or federal, government and its
constituent states' local governments. Unitary government refers to a model in which the
government consists of only one central authority with little or no power granted to individual
provinces. A federal government diffuses power by allowing local provinces to make decisions or
create laws, and creates a hierarchy of governments, typically with the federal government
having more power than individual territories. In a unitary government, provinces have little or
no ability to govern themselves or make decisions; there is only one existing level of
government. A federal style of governance may be most efficient in larger countries to reduce
the strain of governing regions far from the national capital, or in countries with multiple
conflicting groups. For smaller countries, or countries populated almost exclusively by only one
ethnic or religious group, a unitary system may work better. Unitary governments are also
commonly employed by totalitarian governments.