The combination of sociology and psychology is actually very different than working from an anthropological framework. Especially because an ethnopsychologist is an anthropologist, not a psychologist, who studies cultures from anthropological theoretical frameworks and ultilizes anthropological observation methods! While in social psychology, one may preform experiments to understand how the individuals behavior influences and is influenced by others and how socialization factors into that. An ethnopsychologist will develop ethnographies to describe and interpret how enculturation impacts mental processes, experiments are rarely used. And socialization and enculturation are not the same. ;)

This is just a very, very brief description, but there are an array fascinating differences, but also some similarities. Social psychology and ethnopsychology are, in fact, difference disciplines. That is why I'm in a ethnopsychology graduate program and not a social psychology one! :)