Personalities: WW-II involved a lot more interesting personalities - Hitler, Stalin, Churchill, Franklin D. Roosevelt, Hirohito, Eisenhower, Marshall, MacArthur, Rommel, Patton, Montgomery and Mussolini. WW-I personalities were all comparatively insipid. read more
More than 75 million people died due to the large scale of the war which is much more compared to World War I. World War II altered the political alignment and social structure of the world and thus UN formed. read more
the world war 2 was more destructive because more countries participated in ww2 than ww1 and also many destructive weapons were developed after ww1 and at the end of war their was a nuclear attack also. read more
The answer is no doubt a multifaceted one, with most historians attributing the length of the war to, inter alia, the failure of the Schlieffen plan, new types of warfare, technological developments, incompetent generals and the similar strength of the two sides. read more