That’s similar to a car lease plan where you pay monthly over a fixed term and have the option to pay a fee at the end to own the car. The same with the iPhone you don’t legally own the device until you commit to buying it via the final fee. You are essentially renting a phone and not taking up the option to buy it.
The iPhone upgrade program and carrier equivalents are just posh names for rental schemes.
How is it the same? You don’t pay a fee to own the phone like a leased car.