Difference in air pressure is not the only way the wing generates lift. The other way uses Newton's third law. This law state the "Every action has an equal and opposite reaction".


By increasing the wing tilt or angle of attack the wing pushes air down, represented with a yellow arrow in the image on the right. The air deflected downward is the action and generates an equal force upwards, red arrow, called the reaction.
As the angle of attack increases the air flowing over the wing starts to become turbulent and forms an eddy. When the air flowing over the wing becomes turbulent Bernoulli's law no longer applies, lift is reduced and the plane stalls.


The movie on the right shows how turbulence develops above the wing as the angle of attack increases. The pressure patterns necessary for generating lift become unstable and the plane stalls. View the video (from How An Airplane Flies by Shell 1975) on the right explaining how the angle of attack and turbulence cause a plane to stall.