With a standard Xbox controller, all of the buttons and joysticks are locked into a specific position. You’ll have to manipulate your physical position in order to conform to those positions. Whereas on the Xbox Adaptive Controller, third-party switches and joysticks must be purchased.
Each switch and joystick adds to the overall cost of the device but also allows for complete customization. These buttons can then be positioned onto a table or surface around the player in a manner comfortable to their play style.