Within Curatr, an organisation is a logically separate instance of the program. Each organisation has its own URL, its own users and its own courses. Users cannot move between organisations, however, they can have two accounts (one for each organisation).
Each organisation has a name, a URL and a default language. Changing any of these settings after a course has been sent ‘live’ is not advisable; you may render your course inaccessible to users if you change the URL, for example.