Acid reflux is caused by stomach acid coming up into the esophogus. GERD is a form of acid reflux.
Gastroesophageal reflux disease (GERD), gastro-oesophageal reflux disease (GORD), gastric reflux disease, or acid reflux disease is a chronic symptom of mucosal damage caused by stomach acid coming up from the stomach into the esophagus.GERD is usually caused by changes in the barrier between the stomach and the esophagus, including abnormal relaxation of the lower esophageal sphincter, which normally holds the top of the stomach closed; impaired expulsion of gastric reflux from the esophagus, or a hiatal hernia. These changes may be permanent or temporary ('transient').Another kind of acid reflux, which causes respiratory and laryngeal signs and symptoms, is called laryngopharyngeal reflux (LPR) or 'extraesophageal reflux disease' (EERD).
Contributions by Jfdwolff, Kd4ttc, and Cstate2000.