What is the chemical difference between combustion and vaporisation?
The fundamental difference lies in the alteration of molecular structure: combustion at 900°C destroys matter, while vaporization between 180°C and 300°C simply changes its physical state. At the extreme temperature of a lit cigarette, tobacco undergoes an irreversible chemical reaction that creates thousands of tars and toxic gases not originally present.
Conversely, your electronic cigarette keeps the e-liquid below the critical threshold of thermal decomposition, preserving the integrity of PG, VG, and nicotine molecules. As long as you stay within this controlled heating range, you avoid the creation of new unwanted compounds born from a molecular fire. It is precisely this mastery of thermodynamics that radically separates the smoke of a blaze from the purity of a controlled aerosol.