Contradiction in Wings

At the Pentagon, Boeing 757 wings officially struck the outer wall of the building and broke off, exploded and disappeared. The outer wall of the Pentagon was stone, cement and brick, but was not a major load-bearing structure (the building had inner load-bearing columns), and the Pentagon was only five stories tall.

At the WTC South tower, Boeing 767 wings officially struck the outer wall of the building and slid right in according to the videos. In contrast to the Pentagon, the outer wall of the WTC South tower was a major load-bearing structure for a large 30-story building (the amount of tower above the impact zone), and was constructed of massive steel columns.

How can this be?