Basically the terminology is wrong. And that's only because we can't predict the future. Terminology has to evolve too.
If I were to build a logic tree for PV types...I would start with "has electronics?" yes/no branches. So all mech mods would be on one branch and all the other mods on another branch including cig-a-likes. The next branch on the electronics sub-tree would be "removable battery?" yes/no?
Remember that size, mAh and shape are just a matter of current battery technology. So referring to "big battery" is doomed in a future where battery tech is 10x better. It's perfectly possible to imagine a cig-a-like with what is now a 1000 mAh battery ...AKA...eGo cig-a-like at 3.3/3.4 volts and 1000 mAh all in super-mini size. We just need new battery tech. (could be swappable too).
So it's the feature set that has to distinguish. And "having a removable battery" is so common...in everything from watches to whatever, that I don't see it as the first branch. Every PV style has a version with a removable battery...with the possible exception of cig-a-likes. So I don't see it as the first defining characteristic.
Glad to know my watch is advanced....just because I can change the battery.
Watch types are...mechanical or digital as a first category. The mechanical ones you wind. The digital ones have electronics and a battery.
We even jokingly call cigarettes "analogs". Yet a Mech has no "digital" anything unless there's a protection PCB on the battery.
Nah. To me, the 1st defining characteristic is the fact that there is a processor of some type. Because that has broad implications as to all the next choices.