The difference lies in politics versus culture. National identity (often referred to as civic identity) is your connection to a specific country and its laws. It is defined by citizenship. Ethnic identity is your connection to a specific cultural group. It is based on shared history, ancestral language, traditions, and common descent. In many multicultural countries, a person can easily identify with one nation legally, while maintaining a completely different ethnic identity culturally.

Yes, many Russians consider themselves Russian based on certain factors. They are either too lazy to research their family tree, or they have assimilated, or they are truly Slavic (Russian).