All of the above. The below is just one part of the owners manual that explains the different modes, there are a few places that do so check them all out. In addition to the below, the gearing does change in that in Sport mode it stays in lower gears longer to rev the RPMs higher.
From personal experience, I keep mine in Touring mode mostly and with 22 inch wheels, this rig feels super smooth. When I do select Sport, it handles turns like a Camaro!
Driver Mode Control Driver Mode Control attempts to add a sportier feel, provide a more comfortable ride, or assist in different weather conditions or terrain. This system simultaneously changes the software calibration of various sub-systems. Depending on the option package, available features, and mode selected, the suspension, steering, and powertrain will change calibrations to achieve the desired mode characteristics. If the vehicle is equipped with Magnetic Ride Control, selecting the various Driver Modes adjusts the ride of the vehicle to enhance the ride performance for the road conditions and the selected mode. The Driver Mode Control has four modes: Tour, Sport, Snow/Ice, and Tow/Haul. Press the TOW/HAUL switch to activate and deactivate the Tow/ Haul Mode. Press the MODE switch on the center console to select Tour, Sport, or Snow/ Ice. Pressing the switch will display a graphic of all available ride modes and change to the next mode. The Tour and Sport Modes will feel similar on a smooth road. Select a new setting whenever driving conditions change.
Tour Mode
Use for normal city and highway driving to provide a smooth, soft ride. When selected, there will be no indication in the DIC.
Sport Mode
Use where road conditions or personal preference demand a more controlled response. The steering will change to provide more precise control. The Magnetic Ride Control will change to provide better cornering performance. When selected, the Sport Mode indicator will display in the DIC.
Snow/Ice Mode
Use when more traction is needed during slippery conditions. The vehicle will upshift normally when the vehicle is moving. The acceleration will adjust to help provide a smoother launch. When selected, the Snow/Ice Mode indicator will display in the DIC.
Tow/Haul Mode
Tow/Haul is a feature that assists when pulling a heavy trailer or a large or heavy load.