Thinkpad T400s - ATT Gobi vs Verizon Gobi WWAN?

[gravejoker]

Looks like 2 new WWAN options are now showing up for the T400s -
a. Integrated AT&T Mobile Broadband (Gobi 1000 3G with GPS)
b. Integrated Verizon Mobile Broadband (Gobi 1000 3G with GPS)

Does anyone know what's the actual difference between both these options? They seem like the same. But why is there a price difference, if the physical part is the same?

If I buy the one for ATT, will I be able to use for Verizon? or vice versa?

Thanks in advance.

[gravejoker]

Clarification - Gobi WWAN chips support all networks (EV-DO, Rev A, UMTS/HSDPA, Edge/GSM) unlike other WWAN modules. So, this is not a question on hardware limitation. The module itself can support both ATT and Verizon networks.

http://gobianywhere.com/files/gobi1000_overview.pdf

My question was more around the Lenovo restrictions. Does anyone know if I buy the ATT option, does it not allow me to use it on Verizon (some hardware or software lock) or vice versa?