Can any doc tell me what's the difference between electronic cigarettes and smokeless cigarettes?

Theyre all smokeless: because the "smoke" that comes out of these devices is really water vapor, although they have some left over stuff from what you are breathing in, they are not the same as the "side stream" smoke and exhaled smoke from combusted tobacco. If they are nicotine free, they are less dangerous, but we still don't know what the propylene glycol, flavorings, additives etc. etc. do long-term to health.

Both are Vaporizers: The risk is in the liquid used to make the vapor. Flavorless juice has just nicotine and vegetable glycerin. Adding flavoring adds the risk. Strawberries maybe safe to eat but no one knows the long-term effects of inhaling them. Experienced vapers make their own liquids or use only trusted domestic sources who identify all the ingredients they use in their juices. Avoid tobacco-base ejuices