Common Market vs EU

Common Market and EU both are nouns.

Word	Noun	Adjective	Verb	Adverb
Common Market	Yes	No	No	No
EU	Yes	No	No	No

As nouns, Common Market and EU are synonyms defined as:

Common Market and EU: an international organization of European countries formed after World War II to reduce trade barriers and increase cooperation among its members

Other synonyms of Common Market include EC, EEC, Europe, European Community, European Economic Community, European Union.

Common Market (noun)	EU (noun)
an international organization of European countries formed after World War II to reduce trade barriers and increase cooperation among its members	an international organization of European countries formed after World War II to reduce trade barriers and increase cooperation among its members