In organizational research, there is often no systematic distinction between teams, cliques and groups. The reason for this is the definition of groups solely based on the number of people who are in regular social exchange with one another. This article of the journal "Gruppe. Interaktion. Organisation (GIO)" proposes a system-theoretically informed distinction between different systems in the context of organizations. Teams are therefore formal sub-units of organizations. Cliques can be understood as a crystallized form of informality in organizations. Groups-here defined by the formation of personal expectations-can develop as "parasites" in the context of organizations, but do not have to fulfill any function for the organization. Taking into account the different meanings of membership, hierarchies and purposes, the differences between the three system types are explained and the benefits of this differentiation for research and practice are shown.