There are a lot of similarities and differences between the World War 1 and World War 2. A main factor, however, is that the events in the first world war basically caused most of the events to happen in the second world war. The two wars are very closely tied together and have a big relationship with each other.
The ways people fought in the First World War were quite different than the way they fought in the Second World War. World War I started the trend that there was no difference between the citizens of a nation and the military. World War II finishes off this trend by bombing and killing any member of a nation, including the citizens. Life did not matter as much in the Second World War. Trench warfare was common in the First World War, but bombings and sudden aerial attacks, with highly mobile armies were in the Second World War. There were many new weapons that were introduced in World War 1, they changed warfare forever. Airplanes and Poison Gas came about in World War 1 while Nuclear Weapons, Machine Guns, and powerful tanks dominated WW2.
The citizens of the nations involved in World War 1 had their opinions change for World War 2. When World War 1 was starting nobody knew what kind of damage would be caused, most people supported their countries in this war figuring that it wouldn't be as bad as it turned out to be. In World War 2 people have seen the disaster such a big war could cause and most people were reluctant about supporting their countries. Either way, they had no choice but to enter into the war.
The major cause for the First World War was the assassination of the Austrian archduke. This is what started all the bloodshed and battles for the first war. Nobody really saw the First World War coming, and after it was over Woodrow Wilson said it was the "war to end all wars". So many people had died in the First World War and Wilson wanted to get something good out of it, so he tried to approve the Treaty of...