How can you distinguish ANY TI Nspire from another? I dont mean to distinguish CAS vs non CAS or handheld vs non-handheld, etc
Do any unique Nspire features exist that LUA can access or that can be generated?   

ElementCoder : I believe he meant programmatically, from a Lua script

So, yes (but not exactly what you would like, after re-reading your question), especially if the script is going to run on OS 3.2 or later :
See here : http://wiki.inspired-lua.org/platform

Quickly :
[lua]platform.isColorDisplay[/lua]() : Returns true if the display of the host platform is color-capable (Nspire CX and emulator). Returns false if the display is grayscale (Nspire non-CX).
[lua]platform.isDeviceModeRendering[/lua]() : Returns true if the script is running on the hand-held device or in the emulator (with the calculator view), and false if the script is running in the normal view of the emulator.
[lua]platform.isTabletModeRendering[/lua]() : Returns true if the script is running on a tablet device (iPad app) and false otherwise.
[lua]platform.hw[/lua]() : returns a number corresponding to the type of device the script is running on.


No further ways to identify a specific device, though.

Oh I'm terribly sorry I didn't notice it was in the Lua section >< just ignore my comment on this then...
If the hardware is the same then isn't it pretty much impossible?

You could use Ndless lua extensions though