Gastritis is inflammation of the stomach lining, while reflux is the backflow of stomach contents into the esophagus. Gastritis often causes burning or gnawing pain in the upper abdomen (epigastric area), sometimes with nausea and reduced appetite. Reflux more typically presents with burning behind the breastbone, sour/bitter regurgitation, worsening after meals, and worsening when lying down. They can also coexist, and symptoms can overlap. Definitive differentiation is made through clinical assessment and, when needed, endoscopy; Helicobacter pylori is a key factor on the gastritis side. A practical clue: symptoms that worsen when lying down suggest reflux, while pain that increases on an empty stomach may lean toward gastritis. Still, self-diagnosis is not appropriate when alarm signs exist.