How is life in Southern Europe similar to life in the United States? How is it different?

Similarities. Let us start with the most obvious similarity: in the USA, as in the good parts of Europe, citizens use a single currency, identical to the currency of their neighboring States. The borders between the States are also completely open inside the Union. The main difference between the US and the European Community (EEC) is that the former is a proper sovereign state whereas the latter is not. The thing you have to keep in mind is that the EEC was supposed to be an economic union. It actually is but as you can tell it has in practice evolved into more than just that.