980 - 50% longer battery run time than 960 (120 minutes vs 75 minutes)
980 - 2x the suction of the 960 (which already has 5x the suction of the 6xx series)
980 - better carpet cleaning (we never had issues with the 960 on carpet)
Also, the 980 *might* have a better navigation camera. The 960 we have gets lost in really dark rooms at night because the camera kind of blows. I've heard the 980 is better, but that's not confirmed.
The 980 and 960 use the same VSLAM camera system that requires some light to work, it's not LIDAR.
The 960 finishes in 50 minutes what took 870 couple hours to do incompletely (the 870 missed entire areas all the time) -- therefore, the 75 minutes battery of 960 is a non issue for most people since it's so much more efficient than the stupid earlier models. The 960 and 870 use the exact same vacuum mechanism and it's great. The 980 is a waste of money for most people don't buy into the marketing BS unless you're sure you need 45 minutes more battery per session.