Difference between an ORRI & RI?

They may both be free of operating costs but I can almost guarantee neither is free from the ambiguous “ post production expenses” the oil companies love to take. Devon is currently taking 50% on five year old Woodford gas wells that were drilled on a1970’s vintage ORRI that I’m certain should be free of costs. I used to like Devon but now I don’t trust them for a second.