CHICAGO, Oct. 2 (Xinhua) -- Assuming e-cigarettes are equal to cigarettes could lead to misguided research and policy initiatives, a report of the Northwestern University (NU) Medicine said.

"Comparing cigarettes to e-cigarettes can give us a false sense of what dangers exist because it misses the gap in understanding how people use them and how they can make people dependent," said first author Matthew Olonoff, a doctoral student at NU Feinberg School of Medicine.

"Before we start making policy changes, such as controlling nicotine or flavor options in e-cigarettes, we need to better understand what role these unique characteristics have," Olonoff said.

Olonoff listed the key differences between cigarettes and e-cigarettes.

-- The amount of nicotine in e-cigarettes vary widely, which doesn't provide enough consistency for researchers who study the device and smokers' behavior.

-- E-cigarette nicotine is ingested by vaping a liquid; the ability to stop and restart e-cigarettes allows far more variability in intermittent use and nicotine dosing compared to a traditional cigarette.

-- The teen-friendly marketing and technology offered in e-cigarettes makes them more attractive than traditional cigarettes.

-- E-cigarettes are allowed in areas where cigarettes are prohibited.

"They (cigarettes and e-cigarettes) are not interchangeable nicotine delivery systems," he said. "Even though it has the word 'cigarette' in it, e-cigarettes are not the same thing."

E-cigarettes have been commercially available since the mid-2000s. The technology has been advancing rapidly, which makes it nearly impossible to set up-to-date policy initiatives.

When e-cigarettes were introduced, marketing campaigns suggested they could be used to curb cigarette use. But years later, this claim is still unsubstantiated, Olonoff said.

Less than a month ago, the U.S. Food and Drug Administration declared youth vaping an epidemic.

The report was published Sept. 28 in the journal Nicotine &Tobacco Research.