Not all foggies have their optics on the lenses and not all driving lights are clear.
Fog, obviously is for a flat beam directly in front of the car. Driving lights are for when you want to see the road in the next town.
Blazer makes a set of driving lights that fit the fog light holes quite well. The are a tad bit large but I have had them in there before. IIRC they were about $60. I bought them from Checker. The only drawback... They can't be used when other vehicles are in front of you. As my friendly local police officer told me after he followed me home. He was also curious as to why I didn't have a dedicated off switch for them (also illegal in Utah).