Aside from the stench of tobacco cigarette smoke vs. the non-offensive or usually pleasant scents associated with vaping, burning tobacco generates a smoke that is a toxic cocktail of chemicals that affect not only the smoker, but others as well.
Australian scientist Dr Karl Kruszelnicki says the polonium released in tobacco cigarettes is the equivalent to 200 chest x-rays a year for people who smoke a pack of cigarettes every day.
Compare that partial list with chemicals and compounds in e-cigarette vapours: Nicotine Propylene glycol (not Ethylene glycol - which is toxic). Used in asthma inhalers and nebulizers. An experiment using animals determined "air containing these vapors in amounts up to the saturation point is completely harmless". The USA FDA has classified propylene glycol as "generally recognised as safe". Vegetable glycerol - low toxicity. Used in medications, cosmetic and food items.