Both, dew and clouds are formed by water vapor but mechanisms, which produce dew and clouds are different. Dew is formed by condensation of water vapor. Condensation of water vapor takes place on the cold surface of an object.
Dew point is a temperature of surface below which dew is formed. If surface is colder than water vapor and temperature of the surface is colder than dew point, dew is formed. In the dew point water vapor contained in the air reaches saturation necessary to turn it to water. Dew point temperature is not measured precisely yet. It is different for each case and usually is calculated from measurements of wet-bulb depression and dry-bulb temperature. Wet-bulb temperature is usually determined by inducing evaporative cooling. Dew point temperature is affected by humidity. Scientists found out that dew point temperature affects human health. This happens when the temperature exceeds 68 ˚ F.
Clouds are also formed from water vapor. They consist of small water drops or ice crystals. The air in our atmosphere always contains some evaporated water. This air can rise only to certain height till it starts cooling. As soon as it cools and reaches dew point clouds are formed. Water drops or ice crystals form clouds when they are suspended in the air. Water vapor meets some supresaturation conditions, when humidity is more than 100%. Slight supersaturation conditions are enough in order to form clouds.
Both, dew and clouds are formed by water vapor but they are formed under different conditions. Dew is formed when water vapor meets cold surface, cooler than the dew point. Clouds are formed when water vapor is concentrated in the air and humidity level exceeds 100% with the temperature, which riches dew point. Both, clouds and dew are formed under the temperature of dew point but dew is formed on the hard surface and clouds are formed in atmosphere.