The top one means the wagon must not be loosely shunted because it is sensitive to impacts. The bottom one is a stronger version, it must not be loosely shunted and must be properly marshalled by a powered locomotive. Most freight wagons are not sensitive in this way and are sorted in "hump yards" by pushing them by uncoupled loco down the hill, where they are slowed down by static brakes within tracks and eventually stopped by impacting into rest of the parked consist there. But locos cannot be shunted like this at all, and some wagons with technical equipment (refrigerated vans, measuring wagons etc. or in this case probably because of articulated joint) cannot withstand such harsh treatment.
