there is a huge difference.
FP+ is so you don't have to wait in line for the quick service lunch.
ADR is a reservation for the table service dinner.
also the food options are different between lu8nch and dinner.
you are obviously going to get in and out faster at lunch since you order at the touch screen and then get your own drink and silverware and your main dish/side dish and dessert are brought out at the same time.