NATO and the European Union

Regarding NATO and the European Union, how would I go about to describe what they are, how they came into existence and which one of the two is the more important for peace on the European continent, Why would that be the case,  NATO and the European Union (EU) are essential partners who share common values, strategic interests and a majority of member nations. In recent years, the two organisations have developed closer cooperation, focused on concrete results and improved security for European citizens.