How does it differ from sociology?

The unit of analysis is way bigger in sociology, sociology studies more culture and community, where social psychology studies individuals.

Sociology and social psychology are two distinct disciplines within the social sciences, each with its unique focus and scope. The primary difference between the two lies in the unit of analysis. Sociology tends to focus on larger social systems and structures, such as communities, cultures, and societies. It examines how these larger units influence individual and group behaviors. On the other hand, social psychology primarily concentrates on the individual, studying how their thoughts, feelings, and behaviors are influenced by the actual, imagined, or implied presence of others.