"go on" means to continue what you were doing, either an action or a conversation, e.g. "Charlie, I wanted to ask you something.." "go on..." (you are saying that you want them to continue talking/asking the question) Another situation might be that the person talking is interrupted, and so after the interruption you can say, "go on", to indicate that the interruption is over and they should continue what they were saying. (If the interruption is caused by you, it is polite to say "Sorry, please go on"). Whereas, "go ahead" implies that permission is given, e.g. "Fred, can I use your computer?" "Yeah Carl, go ahead" Or informally, "I'm going to get a drink of water" (from your fridge, or tap), "Sure, go ahead" "go ahead" could also be used to indicate that you are ceding your position/giving up power (this does not have to be negative) e.g. You are walking towards the check-out line at the grocery store, you and another person reach the end of the line at the same time, so you kindly say, "go ahead" to them to let them know that they can go first. These are situations when you are letting someone do something before you, or instead of you. I hope these examples are helpful!

Muchacho, tus preguntas aparecen en el área de "Aprender Español", pero veo que estás aprendiendo inglés?