A federal system of government divides power between a central authority and smaller political units, like states or provinces, allowing for a degree of autonomy. In contrast, a unitary system centralizes power in a single national government, which delegates authority to lower levels as deemed necessary. This distinction affects governance structures: federal systems promote local representation and tailored policies, whereas unitary systems can facilitate more uniform policies. Each approach has its advantages and drawbacks, shaping the relationship between citizens and government differently.