well, neither as there is not standard for what the vapour stuff contains...you might be inhaling nicotine and you might not.
"The Chief Medical Officer, Professor Dame Sally Davies, acts as the UK government's principal medical adviser. She has said:
"I believe that electronic cigarettes have the potential to help smokers quit smoking, but at the moment they are not regulated, and some include additional flavourings. The variable quality and lack of data on their long-term safety is such that they cannot be recommended for use." "
http://www.nhs.uk/smokefree/frequently-asked-questions