When is comes to drivetrain and vehicle systems the LR3 and RRS are identical. As for dimensions the LR3 has .6 inches more of ground clearance than the RRS. As for angles of approach, breakover, and departure the LR3 wins, but only by roughly 3 degrees.
Both of these vehicles are equally capable off-road. The true difference, and this is generally true, is the driver. You can have a completely tricked out D2 with lockers, 3-Stage SG suspension, and all the gadgets and still get stuck because of lack of skill and experiece whereas somebody that knows proper off-road driving techniques and the limits of their stock vehicle will not.