That has not been my experience. We are in the U.S. about half the time, and the maps are identical. Moreover, U.S. Service Centers have worked on our Canadian car many times, and Canadian Service Centers have repaired our U.S. car just as often. We have two Signatures, so we are in the SCs a lot.
Importation from Canada to the U.S. is not a problem, but you can NEVER import the other way (U.S. to Canada).
I have not seen any used Model S Canadian prices which were competitive with U.S. after currency conversion. Unless there were a very unusual deal available, it wouldn't seem to make much sense to import from Canada.