Ethnicity is a cultural form of identification, and race is a form of biological identification. Although the two may be interrelated, this is not always the case.
Ethnicity is a group of customs, traditions and rituals with which people identify. Those who identify with the Irish culture, for instance, understand the meaning of its practices. Those people, however, may be of any race. Race, on the other hand, is a biological distinction that people share. Those people who are Caucasian, for example, share similar physical characteristics based on genealogy. They may or may not identify with each others' customs, traditions or rituals.
Many sociologists argue that both race and ethnicity are merely social constructs and that neither exists in actuality. Yet, they are also quick to point out that while ethnicity has been used as a form of self-identification, race is an assignment that is unchangeable. People also do not choose their race. Thus, race is equally a form of privilege and detriment. People of races that are favored, regardless of ethnicity, are privileged while those of races that are considered unfavorable are disadvantaged based solely on physical qualities and in spite of ethnicity. Although race and ethnicity are not always intertwined, society tends to make assumptions about ethnicity based on race.