The executable I modified specifically for SAMP. Now the settings will not be saved in gta_sa.set, but in mta_sa.set. This allows you to use one setting in single player and another in multiplayer. Also useful for owners of licensed versions of the game whose settings are incompatible with exe v1.00 US settings.
Also, you can now add custom tracks to SAMP separately from the single player game. New folder for your music: [SAMP Tracks]
There were other changes, but these are the main ones.