Both ethnicity and race are used to describe one and the same concept from the different angles. Origin can be viewed from a biological and cultural point of view. Biologically, people all over the world have the slightest differences in their DNA which cause minor distinctions in appearance and endow all people with a different skin color. Culturally, people belong to communities which cherish certain traditions, prefer specific clothing, and have a characteristic behavior. Some races include a broad range of ethnic communities which further differentiate people of a single race.
The race is given people by nature. Every child is born with a perfectly-constructed set of external features as well as tendencies towards developing specific diseases. The race is impossible to change or disguise; external features such as skin color and eye shape immediately tell about the racial origin of the person.
Ethnicity, on the contrary, can be changed through the lifetime. Belonging to a certain ethnicity is also given by birth, but as people emigrate, they may change their prior ethnicity. For example, an Asian-American person may live in America but remain the representative of their specific ethnic group like Chinese or Korean. Otherwise, they can assimilate with their new community and become Americans. The matter of ethnicity is to some extent interrelated with a citizenship and religion.
Therefore, race is the heritage which is passed on genetically. It is a permanent characteristic. Originally races indicated that people belong to certain continents, but today people of different races are mixed all over the world. Ethnicity, on the other hand, is a matter of self-identification. People who never emigrated have no difficulties with defining their ethnicity, but those who never settle at one and the same place for too long may find it difficult to tell who they are from the ethnically.