Fog lights are meant to cast a low, diffuse, wide beam directly in front of the car. They are generally used w/ low (main) beams only. The lens has a bunch of prisms/cuts in it to disperse the beam.
Driving lights have a more focused reflector and a clear lens with fewer bevels/prisms. They are typically used to augment high-beams and throw a long, thin beam way ahead of the car.
Two totally different designs.
This is a 914 Euro H3 Hella driving light:
With regards to the 914 switches, I'm not sure but I think the 73- fog switch is orange and the earlier ones green (???). I'm sure somebody else is more up on the switches than me.