The Absence is a prallel universe created by The Order in an attempt to escape from The FBI. The only people conscious of being sent into The Absence were those aware of the presence of the Romidius, the device used as a gateway from The Base to The Absence.
The Absence doesn't necissarily have a point of diversion, but more of differences. This is due to the face it was knowingly created by The Order, rather than created by a choice, which is how most parallel universes in the Ethelverse come into being.
Rather than Zack, Sawyer was killed in the EHS gym
Mrs. Nancy was killed at the Pit, not Saddam. Her death did not destroy the Pit, and it is still in use.
Adam killed Dakot aand John before being killed by Matt
The Death Ray was never constructed
Leslie self-destructed in the fieldhouse, with Mrs. Henry inside.
Kimberly sacraficed herself to kill the Storm.
Jonathan and the Man in the Vents were both killed by The PAAB during the 2012 Pep Finale.
Rather than Mr. Rodgers, Mr. Jones was fought by The PAAB. After the fight, he killled himself.
The FBI and The Order never merged; Mrs. Brush and Mr. Ballard both fought Psypocalypse, with Psypocalypse killing both, but not before Mrs. Brush mortally wounded him.