What is the difference between steam and vapor?

Steam is water in the gas phase. This may occur due to evaporation or due to boiling, where heat is applied until water reaches the enthalpy of vaporization. Steam that is saturated or superheated is invisible; however, "steam" often refers to wet steam, the visible mist or aerosol of water droplets formed as water vapor condenses.

Vapor is a substance in the gas phase at a temperature lower than its critical temperature, which means that the vapor can be condensed to a liquid by increasing the pressure on it without reducing the temperature. A vapor is different from an aerosol. An aerosol is a suspension of tiny particles of liquid, solid, or both within a gas.

The key difference between vapor and steam is that vapor is a generally used term while steam is the technical and specific term. A shared attribute between vapor and steam is the point of origin or how it is formed. Steam and other kinds of vapor are often made by evaporation or with other means or application of heat.