Compare and Contrast: Flight 77 and Flight 93

Officially:

1) Both planes were 757s

2) Both crashed at high speed on 9/11, killing all the passengers, crew and hijackers

3) Both planes disappeared into smallish holes, and leaving behind very little debris (and very little debris from both crashes was ever presented to the public)

4) Both planes exploded violently

5) Both planes spewed small pieces of plane debris from out of their crash holes several hundred feet

6) In the case of flight 93, which went into the ground, very very small pieces of passenger remains (mostly pieces of skin) were found sprinkled at a distance all around the crash site; no such human remains outside the crash site were ever reported for flight 77, which officially went into the Pentagon.

With all the similarities in the circumstances, why the difference in human remains between flight 77 and flight 93?