Question

Distinguish between fog and dew.

Answer 1

Fog is nothing but cloud on ground.The visibility is supposed to be less than one kilometer.Mist is thin fog.The visibility will be between one and two kilometers.
Dew is water in the form of droplets that appear on thin exposed objects in the morning or evening.Water droplets result due to the condensation of moisture at a rate greater than that of which it can evaporate.Dew does not require condensation nuclei(dust or smoke particles) for condensation whereas fog and mist require these nuclei for condensation (just like cloud).

for convenience:

Dew - Water that collects on things overnight.

Fog - A very dense form of mist

Answer 2

$\small\mathcal\green{Distinguish\: between\:fog\:and\:dew.}$

$\huge\mathcal\red{Fog}$

The condensed tiny droplets of water formed by the cooling of air remains suspended in the atmosphere itself . They can be well described as clouds close to the Earth's surface . Fog and mist is the result of condensation around the minute dust particles in the lower atmosphere . This many obstruct visibility If the range of visibility is less than one kilometer , it is termed as fog .

$\huge\mathcal\red{Dew}$

The surface of the earth gets cooled during the night and it cools near the atmosphere . This causes the water vapour to condense and the condensed droplets cling on to the cold surfaces on the earth . This is called dew.