Chronic pancreatitis is a fibroinflammatory disease that is induced by injuries to the interstitial, ductal, and/or acinar cells. The most important causes are alcohol abuse, gene mutations, autoimmune processes, special anatomic changes, and obstructive duct lesions. The morphologic spectrum of the various types of chronic pancreatitis related to the above causes shows features that increasingly allow an etiological distinction and categorization to be made. A catalog of five criteria is presented for distinguishing chronic pancreatitis from ductal adenocarcinoma of the pancreas.