I know the vocabulary of the sentence, but I have never studied the example like this before.

What does an onscreen keyboard allow people with mobility impairments to type using a joystick?

Is everyone with mobility impairments able to use the joystick in order to operate the keyboard on their mobile phones?

An on screen keyboard allows people with mobility impairments to type data using a joystick or a pointing device.

By using a joystick or pointing device, an on-screen keyboard allows people with mobility impairments to type data.

The second sentence states that the onscreen keyboard is the one that uses the joystick or pointing device to allow impaired people to type data.

The difference: In one of them, people use the joystick in order to control the machines in the hall of fame buildings. In one machine, a joystick has to control the machine. Beide of them are true in this case but they aren’t the same.