Annealed Glass
Annealed glass is regular glass, softer than glass that has been thermally treated and is slowly cooled to relieve any internal stresses. When and if broken annealed glass breaks into jagged shards which can result in injury. It is generally used when strength or safety are not primary concerns, and is the least expensive type of glass.

Tempered Glass
Tempered glass is stronger and harder than annealed glass; it is cut and put through a heating process. Tempered glass is annealed glass that has been treated with heat to harden and strengthen the glass. Almost any glass product can be tempered. When and if tempered glass breaks, it will break into small pebble, or pellet pieces. Hence, why it is often referred to as safety glass.

Laminated Safety Glass
Laminated Safety glass is made by adhering two pieces of annealed glass together by a polyvinyl butyral interlayer (PVB). The vinyl layer holds the glass together if the glass is broken.  Impulse burglaries are resisted by the tough plastic interlayer.