First of all i don't think electrons know color coding but they happily flow from positive to negative leaving behind holes that of course move in the opposite direction.
Common or grounds can be sitting at +/- 1000 of volts. So the terminology does not enply nothing except as to say things like ground is common to all our circuits or all returns are common, or all grounds are common. On a 120v ac the white is neutral while the black is considered hot and green earth. Most of house wiring follow this code but not in all of the USA it varies from county to county but all have one law no matter what color you start it better end with the same color.
Common or grounds can be sitting at +/- 1000 of volts. So the terminology does not enply nothing except as to say things like ground is common to all our circuits or all returns are common, or all grounds are common. On a 120v ac the white is neutral while the black is considered hot and green earth. Most of house wiring follow this code but not in all of the USA it varies from county to county but all have one law no matter what color you start it better end with the same color.