||OEM stands for Original Equipment Manufacture. This means that the auto glass meets the original specifications for safety and quality as the glass that it came with from the factory. Auto Manufacturers' do not make glass, they use different autoglass manufacturer's to make the glass for your vehicle.
A "dealer" glass is the same glass the auto glass
shop would have, made from the same auto glass plant, but in the process, the auto glass manufacturer stamps the brand name, such as Toyota, or Ford, making it a "dealer" glass. Same exact glass, but more expensive due to the brand name.