Hey,
the “Process Engine & Infrastructure Diagram” that can be found at the top of the user guide Camunda Platform 7 documentation | docs.camunda.org is deprecated, since the Eclipse Modeler has been replaced with the Camunda Modeler which is used by developers and business analysts alike.
Also the core concept “Delegation Code” is missing in the diagram. More specifically the external tasks are missing as they don’t reside in the runtime container.
Best regards