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.
Nationality means a state of origin in one is born. Every ethnicity belongs to a race, the races of the world being, Latin, caucation, African and Asian, which nationality just means where your born. The reason nationality and ethnicity are synonyms to each other is because the usage of the word nationailty.