Is inflammatory bowel disease (IBD) the same thing as Irritable Bowel Syndrome (IBS)?

No. Inflammatory bowel disease, including UC and CD, is different from irritable bowel syndrome (IBS). Unlike IBD, IBS does not cause inflammation, ulcers or other damage to the bowel. Instead, IBS is a much less serious problem called a functional disorder. This means that the digestive system looks normal but doesn’t work as it should. Symptoms of IBS may include crampy pain, bloating, gas, mucus in the stool, diarrhea and constipation. IBS has also been called spastic colon or spastic bowel

Source: http://www.webmd.com/ibd-crohns-disease/crohns-disease/ibd-versus-ibs