The parliamentary system differs from a federal system primarily in its structure of governance and the relationship between legislative and executive branches. In a parliamentary system, the executive branch derives its legitimacy from the legislature, meaning the government can be dissolved and reconstituted by parliament through votes of no confidence. This system emphasizes party unity and can lead to swift legislative action. In contrast, a federal system divides powers between national and regional governments, allowing both to coexist independently. This separation can result in a more complex governance structure and often includes significant layers of authority.