Different between 水/行 Z600 in Hong Kong

Hi all,

Today I finally got a chance to borrow my friend's 行Z600 to compare to my 水Z600. When I was checking the firmware on both machine I found out that although both Z600 is in traditional chinese, the firmware version is different (See below). Did some testing on both machine and the speed in loading games and pictures seems to be the pretty much the same. The one thing that I don't understand is that how come both firmware are from Hong Kong (said at the end of the version number) but the number is different? Will post some pics here later on this week (don't have a DC with me today).

水Z600 R2D001 prgCXC12-5747_HONG_KONG
行Z600 R2C007 prgCXC12-5747_HONG_KONG

By the way, on the back of my machine it says that it is IDA approved for use in Singapore, but nothing on my friend's apart from a SE行 sticker.

Kelvin