You should be asking about the 'difference' of those phrases. To keep on means to continue to do something (eg. Keep on dancing). Keep going means to continue to travel towards a destination (eg. He keeps going to the club) or it could have the same meaning as keep on (eg. Why do you have to keep going on about that incident?) <----In this case, it means to continue talking about an incident. Lastly, to carry on means to move forward/ move on (eg. At the end of the day, we still have to carry on with life). Hope I helped!