In Assassin’s Creed II, Leonardo da Vinci builds a flying machine for Ezio.
The machine is used during the Venice sequence, allowing Ezio to glide over the city and reach the Palazzo Ducale. Leonardo creates it after studying designs inspired by the flight of birds. The sequence is fictionalized, but it reflects Leonardo’s genuine interest in aeronautics and his surviving studies of wings and mechanical flight.
The flying machine is propelled by heated air and operated as a glider. In the game, burning fires positioned around Venice provide the lift needed for the craft to remain airborne long enough for Ezio to complete the mission. It is a memorable example of Assassin’s Creed blending historical figures with imaginative technology.
The Apple of Eden is a Piece of Eden, not the aircraft. Leonardo also creates upgrades and weapons for Ezio, but those devices are separate from the flying machine. The canonical answer is the simple descriptive name used for the craft in the game.