You could say there are several stark differences between modern-day Manchester United and their rivals Liverpool and Man City. And this has contributed heavily to where they are in the league compared to Ralf Rangnick's side.
They have elite managers in Pep Guardiola and Jurgen Klopp whereas United are in an interim period. They also have well put together teams of accurately-profiled players whereas Rangnick's side is constructed of a number of individuals who don't seem to know how to play together.
But one of the major differences between United and their rivals is a simple one. When they defend they defend as a unit and every member of the team is involved in stopping their opponents from getting a clear chance at goal.