In a federal system, the central (or federal) government has much more authority than in a confederal system. The central government controls more trade policy, and makes decisions about policy areas that involve interactions between states (such as highway systems).
Nationality is a legal relationship between an individual person and a state. Nationality affords the state jurisdiction over the person and affords the person the protection of the state. What these rights and duties are vary from state to state.
citizen(Noun) A person that is a legally recognized as a member of a state, with associated rights and obligations. When the rebellion broke out, the United States promptly evacuated its citizens from the area. citizen(Noun) A member of a state that is not a monarchy; used as antonym to subject. citizen(Noun) A person that is a legally recognized resident of a city or town. citizen(Noun) A resident of any particular place to which the subject feels to belong.