Unitary: characterized by or constituting a form of government in which power is held by one central authority
Confederation: voluntary associations of independent states that, to secure some common purpose
Federal: characterized by or constituting a form of government in which power is divided between one central and several regional authorities
Autocratic: government by one person having unlimited power and citizens have little if any role in the government
Oligarchic: government by the few, small groups exercise control especially in corrupt or selfish purposes. Citizen has very little role.
Democratic: supreme power is vested in the people and is (in) directly exercised
Parliamentary: system have real executive power vested in cabinet composed of members from the legislature (majority) may have a Prime Minister elected by leg.
Presidential: president is constitutionally independent of the legislature