Bile reflux and reflux esophagitis belong to two types of diseases. Reflux esophagitis is caused by the reflux of gastric acid into the esophagus through the cardia due to the relaxation of the cardia, which causes a burning sensation in the esophagus; bile reflux refers to the reflux of bile from the duodenum into the stomach through the pylorus. Therefore, the pathogenesis of the two is different. The substance that damages the gastric mucosa and esophageal mucosa in reflux esophagitis is gastric acid, while the substance that damages the gastric mucosa and esophageal mucosa in bile reflux gastritis is bile. However, bile reflux that breaks through the cardia and refluxes into the esophagus can cause the same damage to the esophageal mucosa as reflux esophagitis, and both have the same microscopic appearance.