This picture is what is holding me up. Look at the South Tower, both the location of the core and also the impact. Now look at the North Tower and it's impact. The South Tower was hit at an angle that sprayed a lot (I do not know the amount) of fuel out of the building in the explosion. The North Tower was hit directly, which meant that it is likely to have had much more fuel in the building, and less being sprayed out of the building. The plane that hit the North Tower went directly into the core, which woudl suggest that it should have done a lot more damage. The plane that hit the South Tower did not hit the core head on, and presumabally did a lot less damage.
To review:
North Tower: More damage, more fuel (more fire)
South Tower: Less damage, less fuel (less fire)
This is confusing considering the South Tower collapsed in 47 minutes and the North Tower collapsed in 104 minutes. If you'd like to focus on that, I'd appreciate it.