New z61ts listed on the tabook

[ThinkZ61]

The tabook has list of new z61ts. tabook

I was wondering if anyone has any idea about the screen brightness difference between 185 and 200 nits.

z60t used to have 1280x768 WXGA with 200 nits
z61t has options of 1280x800 WXGA with 185 nits or
1440x900 WXGA+ with 200 nits

Also, any idea What's the WORKHORSE (W) or GBL (G) stands for in the tabook for any laptops?