RLWL = Remote Location Waiting List
PQWL = Pooled Quota Waiting List
GNWL = General Waiting List
You get these different waiting lists depending on your journey From and To Stations. Generally, if you book a ticket between end-to-end stations, you will get General Waiting List.
These...
more... 3 waiting lists move at different rates depending on the number of seats allocated to the stations, and whether people travelling between those stations are cancelling their tickets.
You Cannot travel in reserved coaches if you have one of these Waiting Lists. You will have to cancel the ticket (and get almost 100 percent refund)
RAC = Reservation Against Cancellation
which is the "next step" after one of the above Waiting Lists. You can travel in your assigned reserved coach, but you will have to share a berth with another passenger, until a vacancy arises en-route.