GND diference

[wjian.2]

There are no diference for conect to gnd in the left side o right side?

[Tesla DeLorean · Accepted solution]

Correct, on the DISCO side they should be on the same plane.

On Arduino shields I'd be more circumspect, and check the continuity, especially proto-shields as they might not have copper/routing between pins of the same designation on either side of the board / connectors.