In general, a vapor phase consists of a phase with two different substances at room temperature, whereas a gas phase consists of a single substance at a defined thermodynamic range, at room temperature. Thus, this is defined as the key differences between Vapor and Gas. You can find the major differences in the table below.
| Vapour | Gas |
| Vapour is a mixture of two or more different phases at room temperature, these phases are liquid and gaseous phase. | Gas usually contains a single thermodynamic state at room temperature. |
| Vapour has a definite shape of the gaseous particles when observed under a microscope. | Gas does not a definite shape when it is observed under a microscope. |
| Vapour consists of random molecules and atoms moving randomly about. | Gas also consists of random molecules and atoms moving about randomly. |
| Vapour is not a state of matter, unlike gases. | Gases are a state of matter. |
| Vapours of water are around us all the time at temperatures below the boiling point of water. | Gases are usually formed above its critical temperature, but below critical pressure. |
For liquid, it have a definite volume, but take the shape of the container. The gases have no definite shape or volume.
gas vs. vapor
Although often used interchangeably, vapors and gases differ primarily in that a vapor is the gaseous state of a substance that normally exists as a liquid or solid under room temperature, while a gas is a substance that naturally exists in a gaseous state at room temperature.
When comparing gas vs. vapor, one must consider the temperature and pressure conditions: a substance is a gas when it’s above its critical temperature and a vapor when it’s below.
In the battle of vapor vs. gas, the key distinction lies in their origin: gases are substances that naturally exist in the gaseous state, while vapors are the gaseous form of substances that are generally in solid or liquid state at room temperature.
The liquid phase is a state of matter characterized by its ability to flow and take the shape of its container, but with a definite volume that doesn’t expand like a gas.
Whether in the liquid or solid state, the behavior and properties of a substance can vary dramatically, including changes in density, malleability, and thermal conductivity.
