Fog and mist, what’s the diff? I distinguish them as follows: Mist is a big cloud that has extended down to the ground. If you flew up a few hundred feet, you’d still be inside the mist cloud. Fog is a low-lying pocket of condensed water droplets. If you flew up a bit, you'd be in the clear, looking down on the fog, and up to the sky or to the clouds above.
However that’s not the official difference. According to the World Meteorological Organization, fog reduces visibility to less than 1 km by water droplets suspended in the air. Mist - not as precisely defined - causes less reduction in visibility. I think my distinction is more romantic, and more fun to use.