I suppose what I'm saying is I'm not seeing much of a difference between the child and adult timeline. I'm sure everyone's explaining it great, but I'm still stumped. I'm looking at the Zelda Wiki and everything. It even says here:
The presence of the Hero who went back and forth in time generated a fork in history, dividing Hyrule's chronology. The Child Link Timeline is the timeline that follows Link after being sent back to his original time following the defeat of Ganondorf by the Hero of Time
The presence of the Hero who went back and forth in time generated a fork in history, dividing Hyrule's chronology. The Adult Link Timeline is the timeline that follows the events after Link is being sent back to his original time, following the Hero of Time's defeat of Ganondorf in the final battle
The child and adult timeline sounds identical. Both involve Link being sent back to his original time by Zelda (because he has to live a normal childhood, etc.).