'Pick and place' feature in connectors
The Pick-and-Place version of the connector will have a piece of tape (probably something like kapton) over the open top end of the connector, or some other firm flat surface, so that a vacuum pick-and-place tip can grab onto it.
After reflow soldering you'd need to remove this tape before the connector can be used.  

This pic (of a different connector, also from DigiKey) shows the tape over the top.



The other version doesn't have the tape, so the top of the connector is just the open hole where you'd later plug in the mating connector, and the vacuum tip of the pick-and-place machine won't be able to grab it.