IBS is a condition without any significant or visible changes to the digestive system. IBD, on the other hand, results in inflammation, ulceration, narrowing, or widening of the digestive system. Treatments of these conditions are also very distinctive, but some overlap exists in certain patients. While the diagnostic criteria for IBS are well defined, and patients may be classified as having this condition, one has to be careful not to miss IBD diagnosis as both conditions may coexist.