A unitary system of government is different from a federal system primarily in how power is distributed.
In a unitary system, all powers are concentrated in a central government, which can delegate authority to regional or local governments but retains the ultimate power to revoke it. This means that provincial or local governments primarily exist to implement the decisions made by the central authority.
In contrast, a federal system divides power between a central government and various regional or state governments. Each level of government has its own responsibilities and powers, which are often protected by a constitution. This allows for a system of checks and balances where different branches of government can operate independently.
Therefore, the correct distinction is: "In a unitary system, all powers are held by one government."