In Android 4.4, CPU is set on the back of screen, now in Android 7.1 CPU and Memory are kept in the box. The innovative design improve the problem of heat dissipation, easier to detach, reduce stock pressure.
The box need to be fixed by band.
Ports on two sides are different, there won't be mistakes in connection.
For dealers client, they could buy more screen and less system according to their own necessity, to reduce stocks.