Is vapor smoke?

No, from a scientific perspective, the "vapor" produced by e-cigarettes is not "smoke".

Although they look similar, they have fundamental differences in physics and chemistry. Here's how you can understand their differences:

Core difference: Burning vs. Heating
Smoke (Smoke): It is the product of combustion. When tobacco (or other organic substances) is ignited, a vigorous oxidation reaction occurs (with open flame), solid substances are incompletely decomposed, releasing solid particles (tar), carbon monoxide, ashes, and thousands of newly formed chemicals.

The "vapor/aerosol" produced by e-cigarettes: It is the product of heating. It is achieved by powering the coil with a battery and heating it, converting the e-liquid (mainly propylene glycol, vegetable glycerin, nicotine, and flavoring) from a liquid state to an gaseous state. This process does not involve combustion, there is no open flame, and there are no tar and carbon monoxide.

Since it is not "smoke", what exactly is it?
In strict scientific terms, what e-cigarettes exhale is not "vapor" (pure H₂O), but aerosol (Aerosol).

Aerosol refers to tiny liquid and solid particles suspended in the air. Common examples like fog, spray paint, and even smog are essentially aerosols.

The particles in the aerosol of e-cigarettes are smaller than the tar particles in traditional cigarettes, but they still contain ultrafine particles, heavy metals, and volatile organic compounds.

Why does it look so similar?
Because they both contain tiny particles. Light scattering occurs when light hits these particles, so they all appear as white, erratic smoke-like substances. But "looking similar" does not mean "being the same thing" - just like soy milk and milk look similar, but their components and production processes are completely different.

 A common metaphor
Smoking is like burning a piece of bread: directly burning the bread into black charcoal, generating black smoke and pungent burnt smell (tar, carbon monoxide).

E-cigarettes are like using a microwave to heat water: heating water to produce steam without a burning process.

It is important to emphasize:
Although "vapor" is not "smoke" and avoids the formation of tar and carbon monoxide from combustion, which typically makes it considered potentially less harmful than traditional cigarettes, this does not mean it is safe. Because this "vapor" (aerosol) still contains substances clearly harmful to health such as nicotine, formaldehyde, heavy metals, etc.

So, scientifically speaking, it is not "smoke", but in terms of health risks, it is still a harmful aerosol that requires vigilance. The safest choice is to stay away from all tobacco and vaping products.