Performance – Glass Bead Reflective Versus Prismatic Reflective – (www.tapedealer.com)
Reflective tape reflects in one of two ways. Either through the use of microscopic glass beads or via man made prisms. Glass bead technology is the oldest and prismatic tapes are more recent.
Note – prismatic reflective tapes were invented by Reflexite Americas in the 60’s.
Glass bead tapes reflect light back less efficiently than prismatics. However, glass bead tape is much less expensive. For applications within a 300 foot range they are fine and sometimes preferable.
Prismatic tape has a tighter more efficient return of light. A brighter, tighter beam extends much further giving prismatic tapes an operating range beyond the thousand foot mark. For marine, highway or traffic applications where long distance conspicuity is important, prismatic is the way to go.
The diagram below shows the dispersant characteristics of each type of tape. Glass bead tape reflects light back sort of like a flood lamp. Up close this is fine. Prismatic tapes shine like a spot light. 
This is better when the viewer is far away.
What is the difference in brightness? Lets compare the color white/silver. White Glass bead tape reflects at about 75 candelas for the standard engineer grade type 1 tape (like your car tag) and 250 candelas for the high intensity type 3 tape. Prismatic tapes start at around 460 candelas and go up to 1000 candelas for SOLAS tape. As you can see there is a big difference in the two tapes. Each has its function and neither will ever become obsolete.