To add few comment from original article:

-991 Turbo S offers sharper throttle response at low revs and in comparison there is a noticable turbo leg below 3000rpm on 650S. Above 4000rpm 650S goes like a starship with warp like till its rev limit.

-991 Turbo S brakes are better on limit and uneven surface. They are better calibrated as well.

-650S is really only marginally faster on the track with ESP off and then it requires more experienced driver with firmer hand. Its traction is amazing for a sportscar with open diff.

-991 Turbo S PDK is way smoother at low speed and city driving. It offers amazing low speed comfort for such a car.