Original Equipment Manufacturer (OEM) refers to parts that are made by the same company that made your vehicle. When you’re ordering OEM parts, you’re ordering parts straight from the manufacturer or local dealer. Aftermarket parts, on the other hand, are parts made by a different company. They’re compatible, but often a lot cheaper. They can often be interchanged with many different brands. While OEM parts are more expensive, they are usually backed by a warranty. However, aftermarket parts can be, and often are equal or better in quality.