The 105UK is variable weighted model, which means the pinky keys are somewhat lighter, thus it is easier to actuate them, and all the keys have gold lettering.
Keyboard Co doesn't have full-sized Topre keyboards in white.
The 105UK has ISO layout, which is the standard layout in the UK.
The 103 has ANSI layout, and the 108 has JIS layout which is the standard layout in Japan.