Fog lamps and driving lights are both different from your vehicle’s high beam. The design of lamps allows them to reflect a horizontal band of light across the vehicle. Inside the lamp is a shield that stops the beam from being projected upwards.
In old times it was advised that fog lamp should be fitted below the vehicle’s front bumper because close to road the fog is very thin and placement of fog lamps low will increase its efficiency. Nowadays, it is much more than lighting efficiency. The value adding characteristics of product and its aesthetics equally matter.