The rich kid tries to impose his superiority (his idea of happiness) over the poor kid by showing off his materialistic possessions to feel good about himself. Thus he picks up a "fight". He tries to break him as hard as he can. However, the poor kid doesn't lose his spirit and decides to keep himself happy with everything "little" he has. In the end, the rich kid accepts his defeat with a realization that he's not content. Also him withdrawing himself from his toys and the tower falling is shown as metaphor of his defeat. "Two" explains the duality of happiness. One that comes from possessions and the other that comes from within.
