Outdoor running differs from treadmill running primarily due to elements like terrain, weather, and psychological factors. Outdoor running presents varying surfaces and inclines, challenging muscles differently than the consistent flat surface of a treadmill. Environmental variables such as wind resistance and temperature can impact performance. Psychologically, outdoor running may offer greater motivation and enjoyment compared to the monotony of treadmill workouts. However, treadmills provide controllable conditions and are beneficial for targeted training, especially in adverse weather.