Comparision of LILLIPUT WinCE GPS devices

I find a lot of WinCE devices from LILLIPUT, does anyone been able to describle the exactly difference between the modles? thanks.
PC-725: 7inch WinCE 5.0 Computer, http://www.zzlilliput.com/html_produ...-725CT-78.html
PC-745: 7inch WinCE 5.0 Computer, http://www.zzlilliput.com/html_produ...-745CT-77.html
PC-746: 7inch WinCE 5.0 Computer, http://www.zzlilliput.com/html_products/PC-746-15.html
PC-765: 7inch IP64 WinCE 6.0 Computer, http://www.zzlilliput.com/html_produ...765CT-104.html
PC-865: 8inch headrest type WinCE 6.0 Computer, http://www.zzlilliput.com/html_produ...865CT-103.html
GK-7000: 7inch WinCE Computer, battery/wifi/BT option, http://www.zzlilliput.com/html_products/GK-7000-22.html

It seems that lilliput's devices do not have GPS inside, all by external GPS antenna, it seems a pity.

I got PC745, PC746, GK7000 in my hand. they belong to same cpu processor, RAM memory, configure. the only difference is the cabling and outer frame. PC746 fixed with a trail cable with 4COM ports. GK7000 with a clumsy apperance because of battery inside consideration.
The newbie PC765 is interesting, IP64, Cortex-A8... I am exciting to get one.