Fogponics is a type of aeroponics where the nutrient solution is aerosolized by a diaphragm vibrating at ultrasonic frequences. This produces drops that are very small, typically with a diameter that stays within the 5-10 µm span. This is much smaller than those produced by ordinary nozzle heads attaced to a pump.
Why are smaller droplets good? Because they diffuse through the air with greater ease and deliver nutrients to the roots without blocking their access to oxygen.