Short answers, pulled from the story.
At its broadest, the Baltic Sea Region includes all nine countries with Baltic coastlines: Denmark, Estonia, Finland, Germany, Latvia, Lithuania, Poland, Russia, and Sweden. The Council of the Baltic Sea States also includes Norway, Iceland, and the European Commission.
Adam of Bremen, an 11th-century German chronicler, was the first to use the name Mare Balticum for the Baltic Sea.
The Baltic states refers specifically to Estonia, Latvia, and Lithuania, which are members of the Baltic Assembly and Baltic Council of Ministers. The Baltic region is a broader term that can include all countries bordering the Baltic Sea, and sometimes Norway, Iceland, and other nations beyond the coast.
The Euroregion B7 Baltic Islands Network includes Aland in Finland, Bornholm in Denmark, Gotland and Oland in Sweden, Hiiumaa and Saaremaa in Estonia, and Rugen in Germany.
The Grand Baltic Entente, also known as the Baltic League, was a negotiating alliance whose members were Finland, Estonia, Latvia, Lithuania, and Poland.
The Baltic Shield is a geological formation that includes Fennoscandia, parts of northwestern Russia, and the northern Baltic Sea. It is a geographic concept based on rock formations rather than political or cultural boundaries.