Both are related to Pipe / tubular structure welding
These are welding position to which a welder / welding procedure is qualified to.
6G is a postion which the tubular weld joint is inclined to 45 degree angle. So welder has to weld the test piece in that postion to get qualification.
6GR means nothing but a restriction ring on that 6G postioned test coupon. 6GR postion qualification is mandatory for welder / procedure qualification of TKY joints in tubular structural construction.