G for green, R for red. They are foreign models, like the UK.
If it doesn't have the G/R at the end of the model number, then it WILL be Blue. The seller might be showing a pic of the G/R model, but ask for the model number if you so choose to purchase it.
To my knowledge they have not released the G/R models to the US yet, that's not to say that they haven't though.
Yep, just bought the CX201 and the CX501 has the switchable illumination. Mine will be blue, with a green illuminated dash......... Crap. I may try to cover the inside of the lens/screen in a fine yellow film to make the blue light appear green. Or may open the face and see if I can swap LEDs. I should have paid attention to the details.