Directional / Non-Directional Alloy Wheels
When a wheel has a turbine style design or has a spoke design that twists to the left or right, you will see that the spokes fan in a clockwise or anti-clockwise direction. When the wheels are fitted to the vehicle, 2 mount to the driver's side and 2 mount to the passenger side, which will change the appearance of the direction from side to side once on the vehicle, unless the wheels have been designed and manufactured as 'directional'.
Non-Directional Alloy Wheels
Essentially all wheels are non-directional unless they are designed to have a separate passenger and driver's side design, so when fitted to the vehicle you will have spokes that appear to go in opposite directions from one side of the vehicle to the other.
For example: On a wheel where the spokes twist (like the image below) you can see that on the passenger side (left) the spoke direction is anti-clockwise, which remains anti-clockwise when fitted to the driver's side (right).
Directional Alloy Wheels
Directional Wheels have an intended passenger side and a driver's side design. So when these are fitted onto the vehicle all the wheels will twist in the same direction whichever side you are looking at.
For example: On a wheel where the spokes twist (like the image below) you can see that on the passenger side (left) the spoke direction is anti-clockwise, and on the driver's side the direction changes to clockwise (right).