Is flow turning different from the Magnus Effect? If so, how?
When air comes into contact with a barn door or whatever at an angle, it will want to follow the top surface down (due to viscosity). Air will try to stick to the surface as much as it could, it usually fails above angle-of-attack of 15° or so.

When the flow sticks, the part exactly at the surface will have zero velocity. Above that part (layer) it will be a bit faster, and so on. Think of the layers within 2-3 cm of the top surface (that's the boundary layer).

Since the top most layer is the fastest, and the bottom is the slowest, the air will turn down (like a tank with different speeds for the different tracks).

The phenomena can be thought of as a force pointing down and causing the air stream to bend. With the airfoil's reaction being an opposite upwards force.

This downward motion pulls air from above and directs it down, causing the downwash. Bringing air from ahead and below is the upwash.

This rushing of air above the surface decreases the pressure, below the opposite happens but at a smaller magnitude. The end result is pressure differential and the air below pushes up toward the lowest pressure.

Flow turning:

Above is considered flow turning, the turning may become more apparent when you look at what happens to the air by a passing airfoil. It is usually depicted like this:



(Sources and more: allstar.fiu.edu, this video, and this video.)

Above is a different frame of reference of looking at how the lift is created. It has nothing to do with the Magnus effect. See PK's answer, both are lift, both can be described in many ways.

The Magnus effect:

The Magnus effect is of usually a spinning cylinder or ball, where the top/bottom surfaces change the speed of the flow in opposite ways. For example, in a back spin, the top surface moves in the same direction as the air stream, further accelerating the air near the top surface and further pulling more upwash, etc.

(Source)