2.1 What the EU is not
The EU is not a federal state. However, it has the trappings of nationhood: an anthem, citizens and governance. It is not the European Economic Area (but belongs to it); it is not the European Free Trade Area. Are you following? Then we can continue the list!
The European Convention on Human Rights (ECHR) is separate from the EU. The ECHR, however, has horizontal application on EU law as its member states are all parties to, and bound by, ECHR and the EU is seeking to become a member in of itself.
European Economic Area (EEA) and European Free Trade Association (EFTA)
Watch the video below. It explains the EEA and EFTA and the relationship between them and EU.
Transcript: The EEA and the EFTA
The relationship between the EEA, EFTA and EU member states is complex: The EU is a member of the EEA. Each member state of the EU has membership of the EEA under that auspice, but not in its own right. Therefore, if an EU member state leaves the EU it also leaves the EEA. Also note there is an update, as since the extract was recorded Croatia has joined the EU.