Patches before the internet and high speed use to be downloaded via modem from the manufacturer. To limit the amount of data that would have to be transfered they just did a binary compare on the new exe to the old exe and only sent the data that was needed to change the old one.
With the internet and higher transfer rates that's no longer needed. just over write the executable with a new one.
With the internet and higher transfer rates that's no longer needed. just over write the executable with a new one.