What was the comparison of World War 1 and 2?

World War I and World War 2 were similar in the fact that all of the major world powers participated, (Germany, Austrian Empire, France, England, Russia, Italy, US and Japan). Both conflicts introduced new concepts of warfare (WWI: trench warfare, mustard gas, tanks, WWII: atomic bombs, Blitzkrieg). Both were brutal wars for their times, (WWI was considered the war to end all wars, WWII is the largest conflict ever in terms of areas in conflict and of casualties). Both shook the world order as it was known at the time.