As far as I know the only difference between the two is that the cal. 2450 has a date display added on the front of the movement, whereas the cal. 2460-1 from the Chronometre Royal does not have a date display. Looking at them from the back they are basically identical other than the rotor which you have stated.
2450 has a date display whereas the 2460 is the "tractor" model upon which extra modules can be added: ie the Patrimony Bi-Retrograde, Les Masques etc...
the fact that the date display is integrated into the movement.