How many version of the HP Prime?

[ctrclckws]

You will likely get more detailed answers. But here's a short take.

The first version of the HP Prime had about 4 iterations.
Original Release
Second Release with additional hardware support.
and then a Third release.
Somewhere in there, the printing on the calculator case was changed to make it more legible.

The second version of the calculator has a newer, faster processor and more memory, and storage.
On the back is an identifying mark G2 in a circle.
I believe the HP model code changed for this model as well, but I don't have a proper reference to confirm what it was.
The Calculator Store indicates "2AP18AA" is this version.

The Wikipedia page for the HP Prime has a section showing versions and model numbers and changes.
https://en.wikipedia.org/wiki/HP_Prime