The main difference between fumes and vapors is that they are made up of different types of particles. Fumes are created when solids burn, while vapors are gaseous substances that have been vaporized from liquids or solids. Both can be harmful to your health, but fumes are more dangerous because they are often invisible to the naked eye.

While fumes can contain a mixture of different substances, including solid particles, vapors are typically composed of molecules that have evaporated from a liquid or solid state. For instance, the fumes produced in metalworking processes contain metal particles, whereas water vapor consists solely of water in its gaseous state.

Fume as a noun is a gas or vapour/vapor that smells strongly or is dangerous to inhale. fumes are solid particles formed by condensation from the gaseous state, e.g. metal oxides from volatilized metals. they can flocculate and coalesce. their particle size is between 0.1 and 1 micron. (a micron is one millionth of a metre) while Vapor as a noun is cloudy diffused matter such as mist, steam or fumes suspended in the air.

Gases are substances that are completely in a gaseous state at normal temperatures and pressures. Some liquids or solids have an associated gaseous phase which is called a vapour. Smoke is a fine solid formed by incomplete burning. Fumes are fine airborne particles produced when a solid vapourises and condenses, eg during welding.