EU means the European Union & EU citizen means EU member countries, citizens
European Union EU countries-
Austria, Belgium, Bulgaria, Croatia, Republic of Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, and the UK.
EEA means the European Economic Area & EEA citizen means EEA member countries, citizens
European Economic Area (EEA) countries-
EU countries plus three European Free Trade Association (EFTA ) countries, Iceland, Liechtenstein, and Norway
CH means Switzerland CH Citizen means Switzerland citizen
Check more about Switzerland Wikipedia
Also, check- What is the difference between EU and EEA?