Im going to vote number 2. Difference was immediately obvious to me. Smoke has those little lingering trails that hang in the air forever. Vapour is kinda thicker looking and in the air shorter.
I am not sure id vape on a plane. Maybe stealth in the airport. I dont do it at the doctors office yet either. I am happy to do it in the supermarket though, openly, and do it virtually every week when I shop.
Interesting matter of cultural "taboo", but so far, anyone whos looked at my vaping in the supermarket or similar, has seen that my e-cig isnt a ciggarette and simply not cared at all.
Back when I had a white model, i used to get "you cant smoke here" occasionally Then id explain, and theyd just shrug and walk away. Not any more though, the visual difference makes the difference obvious, ive not yet been questioned except by the simply curious.
Still negotiating the boundaries personally.
Non-smokers ive been around have been non-plussed if I do it right next to them.
People have been happy for me to vape inside when smoking inside is not allowed.
Without any prior understanding, people seem to automatically consider it different, which is good.
But in highly taboo areas, like planes and doctors offices, or even indoor restaraunts....i dont feel comfortable confronting people's ideas like that, at least at this point in time. I think in a doctors office, or restaraunt, or plane, id probably say nah - people are eating, or sick, or its a confined space. Not that its bad, but its still a smell/chemicals, just courtesy.
Airport itself should really be kosher in theory, its a wide open indoor space. Dont think vaping should be prohibited anywhere, but politeness as a virtue rather than a regulation should be encouraged.