How are clouds and fog similar and different?

Clouds are similar to fog in that they consist of one substance – water, which is in a gaseous state. Water rises into the air, which is in the ground, under the influence of heat and winds.
They differ from each other in density: fogs are less dense than clouds. Also, clouds begin to form at an altitude of two kilometers and can rise above ten kilometers. But fogs form at the surface, and their layer thickness does not exceed a couple of hundred meters. Precipitation is not formed in fogs.