The difference tonight was all in the corners.
Coming out of the tight infield 180, notice Shane doing the standard seat-bounce while Chase manages to get on the pegs and somewhat absorb the jump to stay lower and carry more momentum.
Another view:
I didn't see anyone else do this all night but Chase was getting on the pegs right out of the tight left after the finish to put max weight on the rear wheel and drive straight out of the corner. Beautiful technique.
Last, check out this corner before the whoops. Shane does the typical pivot at the apex and rolls on the throttle as he comes through the apex. But notice Chase gets on the throttle as he's still entering the corner. In this photo, they're both getting on the throttle at the same exact time.
Love watching these two go at it. They put on a clinic tonight and both deserve respect for the way they've ridden this year.