Gastric Sleeve is performed when a Surgeon permanently removes a portion of the stomach (approximately 80%).
Gastric Bypass is when then the Surgeon creates a smaller pouch like stomach and removes most of the stomach along with the first part of the small intestine. The remaining small intestine is then re-routed and connected to the smaller pouch like stomach. A part of the stomach that was removed is attached further down the small intestine. This is done so that acid and digestive enzyemes produced by this area of the stomach can still be provided. Gastric Bypass is a more invasive procedure.