Spherical Reflection(Glass Bead Type)

Each glass bead works as follows : An incoming light beam refracts as it passes through  the front surface of the glass bead and reflected off a mirrored  surface behind the bead again.

The beam then passes back through the front surface, and returns toward the light sources.

Cube corner reflection (Micro-prism Type)

Cube corners are retro-reflective lens elements like glass beads. Each? cube?corner has three mutually perpendicular refractive surfaces.
An incidental light ray is refracted on each of the three surfaces and returned to its source parallel to its initial direction. It functions like a ball bounced into the corner of a room.