Different Localization in front- and backend adds the possibility to use different localization in frontend and backend.
<?php define ('WPLANG', 'de_DE'); ?>
you can specify the frontend’s language as usual.
Inside the plugin file fe-be-localization.php in line 13 you can additionally specify the backend's language, which can (and should!) be different to the one you specified in the wp-config file. For example:
<?php $locale = 'en_US'; ?>