What is the difference between IBD and IBS?

IBD is considered an organic disorder because the disease affects both the tissues and the function of the intestinal tract. Irritable bowel syndrome (IBS), on the other hand, is considered a functional disorder because the intestines aren’t damaged, but they don’t function normally. Whereas IBD is likely an autoimmune disease, IBS is thought to involve the gut-brain axis and the enteric nervous system (nerves that control the GI tract independent of the brain.) Abdominal pain and bloating can occur in both disorders, but more serious symptoms — like bloody stool — would only be present in IBD.^[1]