Localized application contains support for one language and one language only. It always starts on that language no mater on application or operating system settings. You don't have to change your code in order to create localized files.
The following table contains the original English application and German, French and Japanese versions of it.
|Application.exe||Original application file created by development tool. Resources are in English.|
|de\Application.exe||German application file created by Soluling. Identical to the original application except resources are in German.|
|fr\Application.exe||French application file created by Soluling.|
|ja\Application.exe||Japanese application file created by Soluling.|
You only deploy one exe file. If you deploy the German exe file it will always start in German no matter what are the operating system or its settings. Because you have several exe file to choose from the setup file get more complicated and larger. Once installed you can not change the language. This is why some developers prefer multilingual solution where the user can change the language on run time or at least choose in what language the application starts.