* Triple Alliance: Germany, Austria-Hungary, Italy
* Triple Entente: France, Russia, United Kingdom
World War II Alliances
* Axis Powers: Germany, Italy, Japan
* Allied Powers: United States, United Kingdom, Soviet Union, France, China
The main difference between the alliances of World Wars I and II was the inclusion of the United States and the Soviet Union in the Allied Powers during World War II. The United States had remained neutral during World War I, but entered the war in 1917 after the sinking of the Lusitania and other German attacks on American ships. The Soviet Union, which had been formed after the Russian Revolution in 1917, was initially neutral in World War II, but joined the Allied Powers in 1941 after Germany invaded the Soviet Union.
The addition of the United States and the Soviet Union to the Allied Powers significantly shifted the balance of power in favor of the Allies. The United States provided the Allies with much-needed military and economic resources, while the Soviet Union's vast army and industrial base helped to wear down the German military.
Another difference between the alliances of World Wars I and II was the nature of the alliances themselves. The alliances of World War I were more formal and structured, with clear agreements and obligations among the member states. The alliances of World War II, on the other hand, were more flexible and informal, with less clear agreements and obligations. This was due in part to the fact that World War II was a more complex and global war, with many different countries and interests involved.