The 1-2842124-0: That gold thickness supports hundreds of mating cycles — useful if the board goes into field-service equipment where the connector is disconnected and reconnected during maintenance. The 0.110" (2.79 mm) post length gives enough stand-off for through-hole soldering without bottoming out.
Mounting and Orientation for the Board Layout
This is a common choice for mezzanine or card-edge applications where the mating receptacle approaches from the side, not from above. Insulation height is 0.059" (1.50 mm) — low profile, so the header doesn't steal much clearance above the board.