Hi sorry for the late reply as I have missed out this one.
The difference of Z9 and XT9 is the the XT9 is Full Carbon Fibre and Z9 is made up of Alloy Aluminium and a bit of Carbon.
Hence the one that is made of Full Carbon is about 0.5-0.7 kg lighter.
Other than the material the weight the rest is the same for both the Z9 and the XT9 come with LG 8.8 battery, that can cover approximately 20-25 Km per charge. (Look out for other brands who do not state the origin of batteries usually use China batteries)