Different type of players, completely different style. The freeflowing Bundesliga style really benefits Sancho and having other players around him who were part of that smooth, transition style attack. Players like Haaland and Reyna. Not that they're better than the United players, just entirely different. Fernandes and Pogba are great, obviously, but Rashford and Greenwood are EPL sensations. Good enough players but severely overhyped due to being English.
If Sancho has one thing he can rely on its that the lower level of tactics in the EPL will let him run at teams more and beat his man, something he excels at a lot.