I am discussing only two types of vaporization in my question that are, evaporation and boiling. We know that evaporation is the phenomena which describes vaporization of liquid under a certain temperature. And boiling point is the temperature at which vapors of liquid exceeds their pressure by $760\ \mathrm{Torr}$ and starts escaping. The liquid doesn’t absorb more heat and utilize all of the heat to change its state and is said to boil.
There are more details about these two kinds but there is no need to discuss them right now so we should go back to the question that asks that why vapors exerts pressure rather than diffusing in atmosphere.