Pool shock and superchlorination are both methods of adding a high concentration of chlorine to your pool to kill bacteria and other contaminants. The main difference between the two is the concentration of chlorine added. Pool shock typically involves adding a high concentration of chlorine to the pool in one treatment, while superchlorination involves gradually increasing the chlorine levels over a period of time. Superchlorination is typically used as a regular maintenance technique, while pool shock is used to address specific water quality issues.