Compare and contrast the three worlds of the post–World War II order. What was each world attempting to achieve? How successful was each one in achieving these goals?

After World War II, the world was separated into two geopolitical blocks: the Western bloc, which promoted capitalism, and the Eastern bloc, which promoted communism. Thus, the three-world model (the “three worlds” of the Cold War era) that emerged after the war was created to divide the countries of the world into three categories: the First World, the Second World, and the Third World.
The First World (a.k.a. the Western bloc) was led by the US and the North American and European countries that were aligned with NATO (North Atlantic Treaty Organization). The main goal and mission of the First World was to promote capitalism, industrialism, political stability, and socioeconomic development. After the collapse of the Soviet Union in 1991, however, the First World was no longer limited to countries that disapproved of the Soviet regime and instead included countries that were democratic, economically and politically stable, highly developed, modern, and industrially advanced.
The Second World (a.k.a. the Eastern Bloc) was led by the Soviet Union, China, and the countries that were aligned with the 1955 Warsaw Pact (formally known as the Treaty of Friendship, Cooperation and Mutual Assistance), which was formed as a counterpart to NATO. The main goal and mission of the Second World was to promote communism and socialism and to dominate Central and Eastern Europe. With the collapse of the Soviet Union in 1991, most of the Warsaw Pact countries joined NATO, and others were considered underdeveloped or developing countries.
The Third World included the neutral countries that were aligned with neither the First nor the Second World and the developing countries of Asia, Africa, and Latin America.
Essentially, the three-world model was a product of the political tension that arose between the two global superpowers—the Soviet Union and the United States—after the Second World War, which is a period known in history as the Cold War. Today, the three-world model is considered outdated and archaic, and its modern theoretical revisions and definitions focus more on economic and ideological aspects instead of political ones. Thus, politicians, sociologists, and economists use the terms "developed countries," "developing countries," and "underdeveloped countries" to describe the political and socioeconomic climate of the world.