What is the difference between proton pump inhibitors and H2 receptor blockers?

Proton pump inhibitors block the final common pathway of acid secretion by inhibiting the proton pump directly, producing more potent and longer-lasting acid suppression than H2 blockers. H2 receptor blockers like ranitidine, famotidine, and cimetidine block histamine-2 receptors on parietal cells, reducing only the histamine-stimulated component of acid secretion. PPIs are more effective for healing erosive esophagitis and ulcers, while H2 blockers are adequate for mild heartburn and prevention of stress ulcers.