In what way do ethnic groups differ?

Ethnic groups are characterized by distinct cultural traits, which include customs, traditions, and languages that are unique to each group. These cultural aspects are fundamental in defining an ethnic group's identity and differentiating it from others. For instance, the language spoken can influence social interactions, cultural practices, and the transmission of cultural heritage.

While geographical location can influence ethnic differences, it does not solely define them. Political alignments and beliefs, as well as socioeconomic status, can vary widely within a single ethnic group and are not exclusive markers of ethnicity. Therefore, the defining characteristics of ethnic groups primarily stem from their unique customs and languages, making this the most accurate answer.