Segway: Everything is dual redundant. For example, "in the unlikely event of a battery failure, the system is designed to use the second battery to operate the machine and allow it to continue balancing until it is brought to a safe stop."
My scooter: There is no redundancy or backup system. It is not even robustly made. Loose wires literally dangle out the bottom. In the fairly likely event of the software crashing, a wire coming loose, a component failing, or the batteries running low, the wheels will stop and the entire kinetic energy of the system will be used to accelerate my head toward the ground.