Nope, more than likely that the same screen was used for both models because in the lesser model it was still going to be using most of the digits/display so Yamaha could not justify creating a seperate display screen for that model, especially if the screen size due to the spec was also going to be the same.

You see this in a lot of equipment, not just in keyboards but in a lot of electronic devices that share a similar model, the lesser model has the same display but not necessarily all the functions are active. Just cost saving and easy compatability...