[kliclick]

Hi,
Maybe I will buy a Clara HD as my first e-reader, and looking for prices I saw the same device name but different model numbers.
As I understand the Clara HD is N249, but what's the meaning of the other letters/numbers ?
For example N249-KU-BK-K-EP and N249-WM-BK-S-EP.
I can easily understand the "BK" for black... Is the released year or any hardware difference ? Someone knows the coding for these model numbers ?
Thanks