World War I and World War II had several differences. Here is a list of some of the most important ones:
1) Initial involvement- The US entered World War I due to the attack of the Lusitania and the Zimmerman Telegram. These were both actions done by Germany. However, in World War II, the US entered the war because of their poor relationship with Japan and the bombing of Pearl Harbor by the Japanese military on December 7th 1941.
2) Military involvement- During World War I, the US helped with troops in Europe specifically. However, in World War II, the US had to focus on fighting in both Europe and the Pacific Ocean (also known as the Pacific theater).
