Basecamp Options - Device Transfer

I have a new Zumo 590LM. I made a few routes in Basecamp and transferred them to the Zumo. I got a message saying "Route(s) sent to zumo 590 were recalculated because they was created on a map that is not installed on that device." I clicked on the message and it gave me an option to change settings which brought me to the Transfer Settings page.

My Zumo says in has these maps installed:

• Cnna-Na-Dem North America DEM
  
• CN North America NT 2015.40 ALL
  

Basecamp is set to CN North America NT 2015.40 so it seems like the maps match.

I've looked in the Basecamp help and at garminbasecamp.wikispaces.com but I haven't found an explanation of what the Device Transfer settings do under the Edit / Options menu selection. There is a section for Transferring Routes with these options:

• Strip shaping points from routes on transfer to device.
  
• Also send the original route in case I want to recalculate later
  
• Always match route to the map on my device when transferring
  

The option for always matching the route to the map is checked.

Any help explaining this would be appreciated.
Thanks!