While official patch notes from Ubisoft for v1.0.3 focus on stability and visual enhancements, the CODEX version incorporates those fixes plus scene-specific adjustments:
Thus, "Assassins Creed III Remastered Update v1 0 3-CODEX" is not a new game; it is the incremental patch designed to be applied over a base release (typically Assassins.Creed.III.Remastered-CODEX ). It updates the executable and game data from the launch version (v1.0.0) to the stabilized v1.0.3. Assassins Creed III Remastered Update v1 0 3-CODEX