When a node or component is implemented using service based architecture, it mean functionality of that node can be access as a service. Service of a node/component is retrieved through REST interface. Capacity of a node can be shared among different users of that service.
5G core network architecture shows various nodes, interfaces and services. There are few nodes such as AUSF, AMF and SMF used to create a service using the service based interface. However, there are few other components such as gNB and UPF, which are not used to create a service but used as a mandatory component of a service.
Service based Interfaces - Nausf, Namf, Nsmf, Naf, Nudm
Non-service based interfaces - N1, N2, N3, N4 and N6