Experts say the difference between the two has been hidden from consumers for too long.
The glass in the windshield is laminated, which is mandated by law. Laminated glass consists of two pieces of glass with a layer of plastic in the middle, NewsChannel 4's Kyle Anderson reported.
The glass in most side windows is tempered, which means a heating process has taken place, which is aimed at making glass more difficult to break.
Safety advocates believe the difference in the two types of glass is often the difference between life and death.
As consumers, we focus more on the color of a car than any difference in the windshield glass, Anderson reported.
Dr. Carl Clark, a former researcher for the National Highway Traffic Administration, has smashed many windows to convince consumers that laminated glass should be used in all windows.
When tempered glass breaks, the broken pieces are still fairly large, according to Clark. When NewsChannel 4 attempted to break the laminated glass in the windshield, the lamination did not allow penetration.
"There is plenty of room for improvement that the auto industry has chosen not to make," Clark said.
The refusal to make the improvements, according to attorneys, results in lacerated faces, injured eyes and scarred skin caused by tempered glass, Anderson reported.
"One of the myths is tempered glass on the side windows doesn't cut, and it does," said Patrick Ardis, an attorney. "There's over 400,000 documented cases of lacerations a year."
The laminated versus tempered glass issue has been debated internally by auto manufacturers for decades.
A 1969 Ford document noted, "Considering the ease with which tempered side glass can be broken, the use of laminated side glass appears to have a definite advantage as far as restraining the occupant and minimizing ejection."
A 1990 Ford memo said, "For years, many of us have talked about the advantages of using laminated glass in vehicles. However, this idea is rejected due to cost/weight."
In 2001, the NHTA concluded as many as 1,300 lives could be saved if manufacturers would begin using laminated glass for side windows, Anderson reported.
Some manufacturers have started using laminated glass on side windows in luxury vehicles.
A representative for the auto industry believes the reason for switching to laminated glass is to deter theft. Laminated glass is more difficult to break, which makes theft equally more difficult.
Tempered glass is still commonly used for side windows, a situation critics believe has one clear solution.
"The laminated kind of glass -- being stronger -- will prevent a lot of the ejections," Clark said.
Experts said there is a way to tell which type of glass is used in your vehicle.
If the code AS-1 is etched on it, the glass is laminated. If the code is AS-2, the glass is tempered.