Here are brief definitions of each of the terms you provided:
Unitary System: A governance structure where all power resides in a central government. Local governments, if they exist, derive their authority from the central government, which can create or abolish them.
Federal System: A form of government in which power is divided between a central authority and various regional entities (such as states or provinces). Both levels of government have their own rights and powers, usually enshrined in a constitution.
Oligarchy: A system of government where power rests with a small group of people, often defined by wealth, family ties, corporate, or military control. Decisions are made by this elite group without much input from the broader population.
Confederal System: A union of sovereign nations or states that delegate certain powers to a central authority. The central government typically has limited authority, and the member states retain most of the power and independence.
Autocracy: A system of government in which a single person or a small group possesses unlimited power. The leader has complete control over the government and is not subject to legal or constitutional limits.
Democracy: A form of government in which power is vested in the people, who rule either directly or through freely elected representatives. Key features include free and fair elections, civil rights, and a system of checks and balances.
Feel free to ask if you need more information or detail on any of these concepts!