From the Wikipedia page 
An overseas region (French: Région d'outre-mer) is a designation given to the overseas departments that have identical powers to those of the regions of metropolitan France. The overseas regions should not be confused with the overseas collectivities which have a particular status. As integral parts of the French Republic, they are represented in the National Assembly, Senate and Economic and Social Council, elect a Member of the European Parliament (MEP), and use the euro as their currency.
Although these territories have had these political powers since 1982, when France's decentralisation policy dictated that they be given elected regional councils along with other regional powers, the designation overseas regions dates only to the 2003 constitutional change; indeed, the new[when?] wording of the constitution aims to give no precedence to either appellation overseas department or overseas region, although the second is still virtually unused by French media.