The main difference between the two boys lies in their respective motivations for engaging in criminal activity. Blackie's grown up on the wrong side of the tracks; his family has no money and he's never had much of a home life. The Wormsley Common gang is the only real family he's ever had and provides his life with some semblance of direction, albeit in the direction of juvenile delinquency. Crime is second nature to him.
T., on the other hand, should know better, given that he hails from a respectable middle-class background. He commits crime to get back at a society that he holds responsible for his family's coming down in the world. Embittered by his lowly station in life, he takes it upon himself to lead the other boys in their act of wanton destruction against Old Misery's house. In his attitude, if not necessarily his actions, he embodies the leveling spirit of post-war Britain, in which a socialist government sought to effect radical social and economic change.
To a certain extent, the difference in leadership between Blackie and T. represents the shift that the gang has taken from the modern condition. Blackie's leadership is more about the group, suggesting activities that lack social destruction and are more about the group being one with his leadership. T.'s leadership is much more driven towards a particular end. The destruction of this house is something that T. embodies as part of his own being as Greene describes it:
T was giving his order with decision: its was as though this plan had been with him all his life, pondered through the seasons, now in his fifteenth year crystallized with the pain of puberty.
This shows the difference in leadership styles between both. With Blackie, there was less of a directed end to the group. There was a group and its own intrinsic value was embodied by actions taken. With T.'s leadership, there is much more of a directed aim or purpose to the group. This purpose, in terms of destroying the house, is much more driven by social destruction. In their leadership styles, Blackie is more representative of collectivity, while T. is more driven by both a particular end and the sustaining of his own leadership. Both boys take different paths to the same need of validation through the group and their role as leader within it. The significance can be seen as representative of the shift from a communal one to an end driven one in the social setting where distinct destruction is evident, shown in the gutted remains of a bombed out city. T.'s leadership is more reflective of the world in which the boys inhabit and appropriate into their own patterns of recognition. Blackie seems to recognize this in his sulking and even coming late to the start of the house's destruction. His desire to be needed by the group, even when it has shifted from his original aim and intent, is seen in how he needs the group's affirmation, reflecting that in the final analysis, T.'s leadership model has become where the group has moved. In this, the contrast between both boys' model of leadership holds social meaning.