Definitions
A concept is an abstract term that is semantically defined by its association or usage with other terms that are not directly observable (Van de Ven 2007, p. 113). A construct is a middle-range term that references constitutive components of a concept, but the component parts are not directly observable (Van de Ven 2007, p. 113). Events are the natural units of the social process; events are what key actors do or what happens to them (Van de Ven 2007, p. 155).
An example
Consider the social structure of an organization (Van de Ven 2007, p. 114). As a concept, an organization’s social structure is defined as the formal configuration of roles and authority relationships existing among participants within an organization. As a construct, an organization’s social structure is analytically separated into three components of authority relationships among roles: (1) centralization of decision making authority; (2) formalization of rules, policies, and procedures; and (3) complexity, or the number and interdependence of role relationships.
Reference
Van de Ven, A. H. (2007). Engaged scholarship: A guide for organizational and social research. Oxford University Press on Demand.