I apologize for my delay in responding.
The last digits represent the region code for the specifications (plug type, power supply, region code) of the destination for the region or country.
Europe, Asia and the United States all have different plug types, different transmission frequencies (ie: NTSC or PAL) and different power currencies.
I hope that helps.
Anyone know the differencet in these model numbers? I have only seen the last three letters when looking for firmware updates...