- a state with lower-case S is a subdivision of a Federal Country.
- a State with upper-case S is a synonym of Country.
- All members of the EU are States/Countries. Some of these countries are Federal (Germany for instance) and are subdivised into states (Länder in the case of Germany).
- Some States of the EU include multiple Nations. UK is one of these. Scotland is neither a State nor a state for example, but it's a nation.
- Some States of the EU have territories that encompass States that are not members of the EU. Monaco or the Vatican are examples. Some of these States belong to the Eurozone though. http://en.wikipedia.org/wiki/Microstates_and_the_European_Un...