No difference - depends on which country you are in. In UK, NZ and possibly other countries associated with Britain the name is corn flour - in US Canada it is corn starch - just another name for exactly the same thing.
More than 90% of countries do not have the letter p in their name. There are more than 200 recognized countries in the world. There are 9 countries that begin with the letter P. Other than those 9 countries, there are only 11 other countries that include the letter p in their name.
The European Economic Community, or EEC, was founded in 1957 by 6 countries. It now has 27 members and is known as the European Union. So there is no real difference as such. The EU is just the modern name for what was the EEC.
The name in the original Arabic is "Uthman"or "Othman", and not "Usman". The name for the old Turkish "Ottoman" empire was derived from this name. It is part of the Muslims' Urdu language in these two countries to pronounce the "th" as "s", which is not accurate with the original Arabic.