How can i differentiate between cloud and fog?

Question

By using cloud droplet size data how can i differentiate between cloud and fog.

Answer 1

they are both the same thing. a cloud is in the sky and fog is on the ground

Answer 2

The only difference is elevation, clouds are at a higher one than fog, which is at ground level. It is commonly thought that all fog is just low laying clouds, but it can also be caused by cold air moving over warm water, then a slight breeze can move it over land easily.