FIM in a foreign language

Hi. I'm very new to FIM and I am a bit confused about the language packs. 
Can someone explain what the difference is between the following options:
1. Installing the FIM client in a foreign langauge (e.g Italian).
2. Installing the FIM client in the base language (English) and then adding the Italian language pack.
In other words, why does Microsoft bother providing both options? What is the difference?