In International Law, 2 concepts that are used interchangeably are nationality and citizenship.

Nationality and Citizenship

Nationality is a bond that unites a person to a given state, which constitutes his membership in the particular state, that gives him a claim to the protection of that state and which subjects him to the obligation created by the laws of that state .

Citizenship is defined as membership in a political community, one that is personal and more or less lasting, not temporary. By this definition, it can be deemed that a national is one who belongs to a particular political entity and which membership has a characteristic of permanence. Citizenship denotes possession within that particular political community of full civil and political rights subject to particular disqualifications such as minority. Reciprocally, it imposes the duty of allegiance to the political community. A citizen, consequently, is one who owes allegiance to, and is entitled to the protection of the State.

In international law, the term nationality is typically used in place of citizenship, which is understood in municipal law as being possessed of the complete rights and privileges of membership in a political community.