It is each railway zone's discretion how to define berths.
[Example] <From Dadar to Bangalore, the train will have GN quota for DR, PQ, then RL quotas for Pune and Miraj. While from Bangalore to Dadar, the train may have GN quota for Bangalore, PQ, RL quotas for UBL.> So the berth allotments to GN, PQ, different station RL quotas may vary in up and down direction. And hence the number of RAC berths.