@theBitterFig is exactly correct here... the models are different, the ship names are different, and from a legal, technical standpoint, they can't be substituted. The ships may have been interchangeable before, but they are not interchangeable any longer. The different sculpts (and yes, the Rebel and Resistance Falcons have very different details on them across the entire mini, not just the dish) each have their own corresponding dials, pilots, bases, and the like. As stated in the Tournament Regs (bold emphasis mine), "If a player’s ship has different versions in more than one faction, the player may use any version of the miniature and dial that match the full ship name when assembling a squad." A Rebel YT-1300 is a MODIFIED YT-1300, and as such, technically cannot be substituted for a Salvaged or Customized model (or vice versa).
He's also correct in that, in a real world scenario, anyone who rigidly enforces this is a jerk. ![]()