maybe this is the answer

Unicode version can display cyrillic and some other languages characters, if you live in Est europe/greece and want map display the street names in cyrllic than use Unicode, anyway not all devices are supported, NTU update is mostly for new 2012 models and 37xx/2xxx models, in other old models you can have problems by searching address, even the map is recognized by the device in some search you will find no address, in other devices the map is listed on Map info but the device will not show it.