Re: what is the chemical difference between shatterproof and bulletproof glass?

Your question involves three types of materials: (1) inorganic glasses, (2)
organic polymers, and (3)composites of these two types. 
 All of the commercial inorganic glasses are based on vitreous silica, 
SiO2. Pure silicon dioxide can be cooled from its molten state into a very 
transparent and amorphous (i.e.non-crystalline) solid which is a glass. 
This glass, however, has a very high melting point and is expensive to 
shape into useful forms. Consequently, there are many chemically modified 
silicate glasses. Common soda-glass has the composition Na2O.CaO.5SiO2 
with a small amount of aluminum. Potash-glass, or Bohemian glass, contains 
potassium instead of sodium. It has a higher softening point than soda-
glass and is tougher. Pyrex brand glass, useful for lab ware because of 
its low thermal coeffiecient of expansion, is modified with boron oxide.
 Plexiglas(s) was once a trademarked name for the organic polymer poly
(methyl methacrylate).
 Automobile windshields and rear windows are made of laminated saftey 
glass. This is a composite of three layers. There are two layers of glass 
with a layer of organic polymer in the middle. The layers are made into 
one structure by the application of pressure forming a laminate. The 
orgainic polymer has most commonly been poly(vinyl butyral)which belongs 
to the chemical family of organic resins called poly(vinyl) acetals. 
Bullet proof glass is similar to this laminated safety glass but it is 
thicker and is made up of more layers. The patent literature contains many 
inventions to use other polymers in place of poly vinyl butyral.
References:(1) McGraw-Hill Enc. of Science & Technology, 8th Ed. Vol 8, pp 
136-140;(2)Enc. Britannica, 15th Ed. Vol 21, pp 295-307 and pp 760-761,1998