What is the difference between the NordicTrack T 6.5 S and the T 6.5 Si treadmills?

The primary difference between the NordicTrack T 6.5 S and T 6.5 Si treadmills lies in the console features that enhance user interactivity and experience. The NordicTrack T 6.5 Si model includes an upgraded 10-inch interactive HD touchscreen display, which allows users to access a wide range of on-demand workout sessions through iFit, an interactive personal training program. On the other hand, the T 6.5 S model is equipped with a simpler 5-inch backlit display and doesn't include the integrated touchscreen feature. The T 6.5 Si's interactive component encourages more engaging workouts as it can simulate real-world terrains by auto-adjusting incline or speed during iFit workouts, while the T 6.5 S relies more on manual interaction and standard pre-set workout programs.