The difference between the American experience in the two world wars largely has to do with the size and scale of the respective conflicts.
Although World War I was massive and the largest conflict in world history up until then, World War II was significantly larger. About three million Americans served in WWI, while around ten million served in WWII. That meant that life on the home front was more greatly disrupted during WWII, since more young men were gone, serving overseas.
Further disruptions occurred during WWII as nearly the entire industrial output of the United States was converted under the War Production Board to serve the war effort. During WWI, many industries increased production to serve the war, but it was not a total transition in the way it was during the next war.
Another difference between these two wars was the involvement of American women. During WWI, many women temporarily worked in economic sectors vacated by men serving in the military. This also occurred during WWII. However, more women took an active role in the war effort during WWII. In fact, about 350,000 women entered military service, something that was not as accessible to them during WWI.
Perhaps the greatest difference between the two wars as far as the United States was concerned has to do with fighting a war on multiple fronts in WWII. During WWI, US forces fought almost exclusively on the western front in France and Belgium. WWII was a much larger conflict and had Americans fighting in Europe, North Africa, and the Pacific. The Pacific theater was particularly trying, as American soldiers, sailors, and marines were often stationed on remote islands or on ships at sea. This led to more feelings of isolation and deprivation than their counterparts in more populated places in Europe during both wars.