Time
On a scheduled flight the airline sets the time and route. On a private jet you choose the departure time. Arriving at the terminal shortly before departure is enough; the company tells you how early.
Terminal
At most airports, private flights use a separate private flight terminal. No crowds, long queues or distant gates.
Passport and security
On international flights, passport control and security screening also apply on a private jet, but in a separate terminal and much faster.
Choice of airport
Private jets can also land at small airports without scheduled service. That means landing closer to where you are going.
Price
On a scheduled flight the price is per person. On a private jet the price is for the whole aircraft; for a larger group, the amount per person can be more reasonable than expected. Jets returning empty (empty legs) can offer a lower price on the same route.