Bulletproof glass is completely different from any normal glass. Although it is not possible to prove a full bullet in a glass, it would be more useful to call bullet resistant or bulb resistant glass; It means that in some cases it is able to prevent the shot. It is not a glass, originally made of sturdy glass of many layers and made of different types of plastics in each level.
The final level of many glass inside is made of poly carbonate, which is a great quality solid plastic. A solid glass is then strong plastic and glass again plastic is thus made up to many levels, this glass is made entirely and this process is called lamination. This process makes bulletproof glass much thicker than normal glass. The resistant glass density usually ranges from 7 millimeters to 75 millimeters.
When a bullet hit the bullet in the bullet, the bullets of energy are spread across the sideways. Because the bullet's energy is divided into several parts; Instead of just crossing a single glass, here's a tough glass together then a strong plastic glass again, again the plastic needs to overcome a few levels. Due to many layers, the bullet energy spreads all the way around and its energy is absorbed by different layers. The speed of the bullet does not remain the same as it is absorbed by the energy, it gets completely stuck in one level and the ability to penetrate the final layer before it is lost. Think Bulletproof Glass is a "energy absorbent" glass, you can get a better idea.