T610 & R710 Questions

Hi

Could any tell me what the differences are between the T610 Gen1 And Gen2

and also for the R710?

Also

I have been told that the motherboard is tied to the windows license and when you install the O/s you don't require a key it does it automatically, is this correct.

if so, if i purchase a system with no license or replace a board can i tie it to the motherboard manually?

Hope that makes sense

Thanks