I call it retro-reflective, just like the street signs that concentrate more light back toward the headlights on a car at night to try to increase the signs visibility of the sign to the driver of the car. Little glass beads do the trick.
It should be easy to verify just with a flashlight and looking at the screen material, like by putting the screen material against a normal wall and seeing how the screen material sends more light back toward the source.
You likely know this, but just for clarity, with an angular-reflective screen with gain a ceiling mount would have the most light to a viewer closer to the floor, like drhankz suggested. That is assuming the screen is placed vertically or tilted down instead of tilted up. Tilting a retro-reflective screen has little effect since it is still trying to send more of the light back toward the source and not to a spot that a flat mirror would reflect the light toward.