Internationalization in magento can be achieved by 3 different configuratons
1. create different websites:
Creating different websites in magento allows you have different website orders, different website customers, different catalog etc. So basically this is like having totally different magento website’s running inside a single admin
2. create a new store:
Creating a new store allows you have different root catalog. e.g You might want to sell different categories/product in one country and in other country you want to sell different catalog. But overall you only have a single website i.e customers, cms pages, order etc.
3. create a new store view:
This only allows you have a two different language/designs rest all is same.
So depending on your requirement this is how you need to plan.