The difference between Hirose Part number GT17HN2-4DP-2H(C)(56) and GT17HN2-4DP-2H(C)(57) is surface mount vs through hole. Please see the drawings below.
(56) drawing:
https://www.hirose.com/en/product/document?clcode=CL0767-0295-1-56&productname=GT17HN2-4DP-2H(C)(56)&series=GT17H__HN&documenttype=2DDrawing&lang=en&documentid=0001393023
(57) drawing:
https://www.hirose.com/en/product/document?clcode=CL0767-0295-1-57&productname=GT17HN2-4DP-2H(C)(57)&series=GT17H__HN&documenttype=2DDrawing&lang=en&documentid=0001396351