The ending depends on a combination of 2 conditions, which are whether or not you could see Kaufmann at the motel office, and if you could save Cybil.
On top of these, there is the 5th ending, commonly known as the UFO ending.

7 normally.
There are 4 more in addition to those.

It is used to collect the liquid on the floor of the Director's office in the real world hospital.
There is no other use for this.

At close range (a range in which a strike-weapon can be used), utilize the "Red Liquid".
If you did not collect the liquid in the plastic bottle in the Director's office in the real world hospital, you have no way of saving her.

That resides inside your imagination, and that is the truth about what fell on Silent Hill.