In aviation, by definition gliding is unpowered flight, like coasting in a car. If you're doing performance calculations, there are different equations for gliding and powered flight.

Ballons aren't gliding.

Helicopters and quadcopters also aren't gliding.

Helicopters and quadcopters provide lift through rotary wings, thereby gliding. Fair point about balloons though.

That's like saying cars are moving by turning (because their wheels do that).

Cars are moved by turning though. From the pistons driving the engine, through the gearbox and drivetrain to the wheels.