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.