That's correct. Unless you're willing to modify some domes one way or the other to create cutouts for LEDs and what not you'll have an imperfect swap.
On my boards the 55g HiPro has a 45g Esc, PrtSc, Scroll Lock, Pause, and numpad, and the 45g 87U (not pictured here, I have a white one) has 55g on LCtrl, PrtSc, Scroll Lock, and Pause IIRC. I did the swap hastily and didn't take photos or notes. That's okay, I plan to open the both up later to install damping rings.