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Steam vs. Vapor: What's the Difference?

Edited by Harlon Moss || By Aimie Carlson || Published on December 15, 2023
Steam is water in its gaseous form produced by boiling, visible as mist or condensation, while vapor is any substance in gas form, often invisible, at temperatures below boiling.

Key Differences

Steam specifically refers to the gaseous state of water when it is heated to the boiling point, forming a hot mist. It's often visible due to the tiny water droplets formed when steam condenses in the air. On the other hand, vapor refers to the gas phase of any substance that normally exists as a liquid or solid at room temperature. Vapors are typically invisible, as they are at temperatures where the substance is not fully converted to gas.
In everyday language, steam is commonly associated with boiling water, used in cooking or produced by steam engines. It's visible, especially when cooling down and condensing into water droplets. However, vapor is a broader term that encompasses any gaseous form of a substance that is not at its normal gaseous state, like the vapor of alcohol or gasoline, usually invisible and occurring without boiling.
Steam carries significant amounts of thermal energy, which is why it's used in heating systems and power generation. The energy in steam comes from water's phase change from liquid to gas. Conversely, vapor may not have the same level of energy since it forms at temperatures below the boiling point, through evaporation or sublimation, like water vapor in the air.
In industrial contexts, steam is crucial for its mechanical properties, as in steam turbines and engines, where its expansion drives machinery. It's a controlled and high-energy state of water. In contrast, vapor is often discussed in terms of its chemical properties, like in the case of vaporized solvents in chemical processes, focusing on its state of matter rather than energy content.
Steam becomes visible when it cools and condenses, forming a mist of tiny water droplets. This is a common phenomenon seen during cooking or in steam baths. Vapor, though, often remains invisible even as it cools, unless it reaches a point where it condenses back to liquid, like dew forming from water vapor.

Comparison Chart


Gaseous state of water at boiling point
Gas phase of a substance below boiling point


Often visible as mist
Typically invisible

Energy Content

High energy, due to phase change
Lower energy, forms without boiling

Common Use

In heating and power generation
In chemical processes and natural evaporation


Visible when cooling
Invisible unless it condenses into liquid

Steam and Vapor Definitions


Visible gas emitted from heated water.
Steam rose from the hot soup in the bowl.


Invisible gas formed by evaporation.
Water vapor contributes to the humidity in the air.


The mist formed when steam condenses.
Steam fogged up the bathroom mirror after a hot shower.


A gas phase of a liquid or solid at room temperature.
Gasoline vapor can be flammable.


Water in its gaseous state, produced by boiling.
The kettle released steam as the water boiled.


The diffuse gas produced without boiling.
Vapor from the wet ground rises in the morning sun.


The vapor phase of water used for energy.
The old locomotive was powered by steam.


The substance in gas form released naturally.
The morning air was filled with the vapor of dew.


A cloud of vaporized water droplets.
Steam enveloped the kitchen as she opened the pressure cooker.


The gaseous form of a substance below its boiling point.
Alcohol vapor is released during the fermentation process.


Hot water vapor produced especially by boiling liquid water.


The gaseous state of a substance that is liquid or solid at room temperature.


A faintly visible suspension of fine particles of matter in the air, as mist, fumes, or smoke.


What exactly is steam?

Steam is the gaseous state of water, produced when it reaches the boiling point.

Is steam visible under all conditions?

Steam is usually visible when it cools and condenses into tiny water droplets.

What causes steam to form in cooking?

Steam forms in cooking when water reaches its boiling point and turns into gas.

Is vapor always invisible?

Vapor is typically invisible, although it can become visible when it condenses.

What are common uses of steam in households?

In households, steam is commonly used for cooking, heating, and cleaning.

How is vapor different from steam?

Vapor is the gas phase of any substance below its boiling point, often invisible, whereas steam is specifically water vapor at boiling temperature and usually visible.

Why is steam used in power generation?

Steam carries high thermal energy, making it efficient for driving turbines and engines in power generation.

Can all liquids form vapor?

Yes, most liquids can form vapor through evaporation or sublimation.

How does water vapor affect weather?

Water vapor plays a crucial role in weather, contributing to humidity, clouds, and precipitation.

How does vapor pressure relate to boiling?

Vapor pressure is the pressure at which a liquid starts to become gas; when it equals atmospheric pressure, boiling occurs.

How is steam generated in a power plant?

In a power plant, steam is generated by heating water in boilers until it vaporizes.

What is the role of vapor in the greenhouse effect?

Water vapor is a significant greenhouse gas, trapping heat in the Earth's atmosphere.

Does the presence of vapor affect air quality?

Yes, certain vapors like industrial emissions can significantly affect air quality.

How does vaporization differ from evaporation?

Vaporization is the general process of turning into gas, while evaporation specifically refers to surface liquid turning into gas.

Can steam be dangerous?

Steam can be dangerous due to its high temperature and energy, potentially causing burns.

Can vapor be used in industrial processes?

Yes, vaporized chemicals are often used in various industrial and chemical processes.

Is it possible to see water vapor?

Water vapor itself is invisible, but it becomes visible when it cools and condenses into mist or clouds.

Why is steam often used for sterilization?

Steam is used for sterilization due to its ability to carry heat, effectively killing bacteria and microorganisms.

Can steam be at a temperature higher than boiling point?

Yes, steam can be superheated, existing at temperatures higher than water's boiling point.

Is the steam from a shower the same as from a kettle?

Yes, the steam from both a shower and a kettle is water in its gaseous state, although the context and quantity may differ.
About Author
Written by
Aimie Carlson
Aimie Carlson, holding a master's degree in English literature, is a fervent English language enthusiast. She lends her writing talents to Difference Wiki, a prominent website that specializes in comparisons, offering readers insightful analyses that both captivate and inform.
Edited by
Harlon Moss
Harlon is a seasoned quality moderator and accomplished content writer for Difference Wiki. An alumnus of the prestigious University of California, he earned his degree in Computer Science. Leveraging his academic background, Harlon brings a meticulous and informed perspective to his work, ensuring content accuracy and excellence.

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