I don't recall the FDA referring to e-cigarettes as ENDS.
Rather, this is a term that's been used by several different researchers (including Murray Laugesen as I recall, although one of his articles called them Electronic Nictoine Delivery Devices or ENDDS).
A decade ago Ken Warner coined the term PREPS (Potential Reduced Exposure Products) to describe any tobacco/nicotine product that is less hazardous than cigarettes (in an effort to cast doubt that smokefree products are less hazardous than cigarettes unless/until manufacturers and others spend lots of money proving the obvious). Warner originally proposed PERPS (Potential Exposure Reduction Products), but he replaced it with PREPS because PERPS refers to perpetrators of crime.
The term PREPS has been used by many tobacco product researchers used for the past decade.
With enactment of the FSPTCA, two new terms that are being used to describe smokefree tobacco/nicotine alternatives to cigarettes include Modified Risk Tobacco Products and Reduced Exposure Tobacco Products.
And since the FSPTCA requires companies to apply to the FDA, and for the FDA to approve, any Modified Risk or Reduced Exposure claims, it is now a federal crime for any smokefree tobacco product manufacturer or importer to truthfully state their product is less hazardous or exposes users to fewer contaminants than cigarettes.