A "context", "scope", or "system context" diagram models the project product or major deliverable by a simple representation of it in key business contexts. These contexts are a) the main end-users and b) the systems by which they use it. The diagram focuses on relationships, not flows or what "inside" the system. Such a diagram usefully supports both project charters and the process of gathering requirements, the key project management job following charter approval.
A context diagram models a project product by a simple representation of it in key contexts. These contexts are a) the main end-users and b) the systems by which they use it. There is no modeling of what is "inside" the system. In this diagram, the "system" whose context is modeled is a role, that is, a service or set of human activities. The context of the role here seems to be an ongoing relationship of Wikipedia to GLAM (Galleries, Libraries, Archives, and Museums) institutions.
An example of use case diagram for an airport check-in and security screening - Passenger, Tour Guide, Minor (Child), Passenger with Special Needs, all playing external roles in relation to the airport business.