How are World War two and World War I the same?

World War I and World War II are different wars. Many effects of World War I led to World War II, but they were separate, independent wars.

The wars were similar in that they both involved France, Russia, Britain and the Commonwealth countries, and the United States, fighting against Germany.

There were also strategic similarities between the wars, for instance, Germany, in both wars, relied mainly on U-boats (submarines) to attack the merchant ships of the western allies, rather than using her surface fleet to any great extent.