What is the difference between Ro and Gy interface of diameter?

Question

As per my understanding both are same but could not confirm the same from internet so asking this question.

Answer 1

Gy is mostly a restricted subset of Ro. For instance, in Gy online charging the use of multiple-services-credit-control AVP is mandatory. Gy also adds some AVPs that Ro doesn't specify (eg. volume-quota-threshold).

Answer 2

Ro is a 3GPP reference point that describes the connection to the OCS from another functional component. It is a general term that covers multiple connecting components such as GGSN, P-GW, WLAN, IMS AS, MBMS server, etc. See 3GPP TS 32.296 [1] Figure 5.1 for reference.

Gy is an specific instance of the Ro reference point that connects a charging component from the packet-switched domain (PS domain) i.e. PCEF within a GGSN or P-GW to the OCS. See 3GPP TS 32.251 [2] Figure 4.3-1 for reference.