1) The federal, confederation and unitary systems represent distinct forms of governance. In a federal system, citizens possess the right to vote and actively participate in government affairs. In contrast, in a confederation, citizens wield more authority, while in a unitary system, the central government holds significant power, often overshadowing citizen input.

2) The structure of the US government operates on a federal level, featuring three branches: executive, legislative, and judicial. The legislative branch crafts laws, the executive branch enforces them, and the judicial branch interprets them. Moreover, the government functions across national and subnational tiers. At the national level, the federal government addresses issues of national significance, including defense and economic policies. At the sub-national level, individual state governments manage localized matters such as education, public services, and healthcare.

3) The federal government influences the actions of state and local governments through various means, including financial assistance and policy initiatives. For instance, amidst the pandemic, the federal government increased funding for scientific research, testing, treatment, and vaccine distribution. This financial support enables state and local authorities to implement effective public health measures and provide affordable healthcare services to their residents.