What is the difference between the 20 hours minimum sport pilot flight training hours and 40 hours minimum private pilot training hours?

Less training is required because there is no night flight training, high altitude procedures above 10,000 feet, control tower operations and radio navigation/VOR requirements (no new pilots use these anyway ' it is all GPS). However, Sport Pilots can receive additional training beyond the 20 hours minimum required training for Sport Pilots and be endorsed to operate at larger 'control towered airports' Class B, C and D.