None of them are what you think they are, Ahladgor.
Some people have this understanding that there are no ETs or Aliens, only Fallen Angels and their brood (from laying with human women,) the Nephilim. They say that these Reptilians are actually of the old Nephilim blood line, and that all UFOs and ETs, are either Fallen Angels or Demons taking on various forms. Supposedly, these Fallen Angels can take on any shape or form imaginable, including the 'good' ETs like the Nordics or Pleiadians. Those other ET races are just another form of these beings, looking to deceive us all - good cop, bad cop kind of thing.
No one can say for sure who or what they are, unless they're one of them, and even then it won't be a straight answer.
Interesting Docu on the matter-
Aliens are Fallen Angels and Demons From Hell, there's 4 parts to it, some very interesting footage.