When Nightly or Developer Edition are installed into a new location, the desktop and start menu shortcuts don't point to that location. I think this happens because of the way the migration checks are written (start menu, desktop): If the old BrandFullName shortcut exists we try to migrate it to the new BrandShortName instead of creating a new shortcut, but if it had a different target then nothing is done. Because BrandShortName and BrandFullName are the same for Nightly ("Firefox Nightly" in BFN, BSN via MOZ_APP_DISPLAYNAME) and Developer Edition ("Firefox Developer Edition" BFN and BSN). Release doesn't work that way (BFN "Mozilla Firefox", BSN via MOZ_APP_DISPLAYNAME "Firefox").

Ultimately this may not be too important, but it was puzzling.