Nationality is basically restricted to the constitute states (England, Wales, Northern Ireland, Scotland) and can also include a common, British nationality. It is more determined by where someone was born and raised.
Ethnicity can encompass background from other continents: for example, British English, Jamaican English - Ethnicity reflects people's family backgrounds
Nationality is the relationship between a person and the political state to which he belongs or is affiliated. Ethnicity is the identification of a person with a particular racial, cultural, or religious group.
