It's more a difference of speed. A less known fact is that rockets and orbital mechanics is more about going fast than it is going high.
The booster has a max speed of mach 5 before it returns to the tower. The upper stage which landed had a max speed of mach 25 which has to be shed off somehow without breaking the ship!
The booster has a max speed of mach 5 before it returns to the tower. The upper stage which landed had a max speed of mach 25 which has to be shed off somehow without breaking the ship!