Based on the research I was able to find the FDA does regulate all cigarettes, smokeless (e-cigs), and roll your own tobacco and these regulations have been in effect since 2009. On August 8th, 201 the FDA finalized a rule to regulate ALL tobacco products.
In my opinion I do not think there is a difference between cigarettes and e-cigs in terms of regulation. Both are products or devices which allow the user to inhale chemicals into their body. Regardless of the delivery system, the end user is still ingesting harmful chemicals that can affect their health. From this standpoint I feel that both products should share the same regulations.
As I mentioned above, the FDA does in fact regulate normal cigarettes and has been since 2009.
In my opinion, I do believe that e-cigs should be a considered a drug delivery device (class III medical device) since a large part of that determination is based on risk. Since there is not a substantial evidence which details the long term effects of e-cigs, I believe there is still a lot of medical risk associated with these products. There should be a much deeper understanding of the ingredients (chemicals) that go into the e-cigs in combination with its delivery system (water vapor), and how all it affects the human body. Until we have this knowledge we should be treating these products with a much high risk level, which should the in turn demand the control (regulations) of these products.