#2 Pressing from the front and quick transitions
The most visible change in United's playing style has been their pressing. Last season, it appeared disjointed and lacked cohesion. However in pre-season to date, that lack of cohesion is nowhere to be seen: they didn't allow Inter an opportunity to settle into the game, particularly in midfield battles.
Whenever Antonio Conte's men attempted to pass their way out of the back, United were all over them and forced them into relinquishing possession often in dangerous areas. Also, whenever United themselves lost the ball, they refused to drop off and invite pressure.
Instead, they were all pressing to win the ball back and caught Inter off-guard. Another thing that you can see is their quick transitions from defence to attack. The pace in that United attacking setup is frightening and whenever they won possession in their defensive third, the swarming red shirts were bombing forward in numbers to cause all sorts of problems for the Inter backline.