@ZipLine-- The article mentioned that rebound tenderness is when there is pain after pressure is released, not when it's applied. That's the difference between abdominal tenderness and rebound tenderness.
If there is abdominal tenderness, the patient will feel pain when pressure is applied to the abdomen. In rebound tenderness, the patient will not feel pain when pressure is applied. He or she will experience pain only when the doctor removes pressure.
Abdominal tenderness shows that the abdomen is inflamed and sore. Rebound tenderness shows that the outer layer of the abdomen is unable to tolerate stretching.