What is the difference between Anthropology and Sociology?

In the early 20th century the difference was one of division of labor - sociologists were said to study literate, more "modern" or complex societies, whereas anthropologists studied pre-literate, "primitive", or "simple" societies. However, since the 1930s, anthropologists have studied groups in urban settings and in the U.S.  Conversely, any sociologists study social phenomena outside of Europe and North America. Anthropologists pioneered techniques of fieldwork and participant observation, but today many sociologists use these as well. Cultural anthropologists draw on much of the same social theory as sociologists. Many cultural anthropologists are in conversation with the other subfields of anthropology, which consider social phenomena in the light of adaptation, human evolution, and the prehistoric record - something sociologists are less likely to do. That said, many anthropologists and sociologists today are studying the same social phenomena, in the same places. Because of this, integrated Anthropology and Sociology programs are not uncommon.