Every 4G EPC node has a corresponding 5G NF, but the mapping is not one-to-one. The MME was split into AMF (Access and Mobility Management Function) and SMF (Session Management Function) to better separate mobility from session management. The SGW and PGW merged into the UPF (User Plane Function), while the HSS became UDM+UDR and the PCRF became PCF.