(1) water vapor: abbreviated as water vapor or steam, it is the gaseous form of water. When water reaches the boiling point, it becomes steam. At standard atmospheric pressure at sea level, the boiling point of water is 99.974 degrees Celsius.

(2) Steam: refers to the existence of water in a specific space in the form of gas-liquid two-phase, in which the liquid phase can exist in the form of "fog" dispersion or in the form of a large number of droplets aggregation.

2. Different characteristics

(1) water vapor: it is an inorganic substance composed of hydrogen and oxygen, and it is a colorless and odorless transparent liquid at normal temperature and pressure. In nature, pure water is very rare. Water is usually a solution of acid, alkali, salt and other substances, and is still customarily called water.

(2) Steam: When water is placed in a sealed container that has been vented, molecules will escape from the water surface, and at the same time, molecules will return to the water from the steam space. At the same time, if the number of molecules escaping from and returning to the water is the same and reaches a dynamic balance, water and steam will be in a saturated state, which are called saturated water and saturated steam respectively.

3. Different applications

(1) Water vapor: Water vapor is not an energy source, nor a secondary energy source, nor a renewable energy source. Water vapor is just a manifestation of water in gaseous state.

(2) Steam: Heat energy can be converted into mechanical energy, and liquid can be heated and evaporated.