It is believed by many that OES (original equipment supplier) parts are to be purchased directly from the dealer. OES parts are built on the same assembly line as OEMs (original equipment manufacturers), except through a few added steps. Branding of part or stamping with manufacturer logo IE: Honda, and then wrapped and labeled in manufacturers packaging. This OES portion has become more expensive for the consumer as the thesis steps have been inflated by many middlemen. There are quite a few OEM companies on the market due to ISO (International Organization for Standardization) certification regulations as many OES brands are required. For auto manufacturers to have a stable supply on the production line, they must have multiple supply sources that provide them with the same quality parts. This ensures that if a manufacturer has a problem with one supplier it will not disable the production of vehicles and will allow replacement of other brands for production, repair and warranty replacement.
Aftermarket parts are copies of OEM parts. These car spare part dealers are designed to be more economically viable replacement parts than an OEM part. These parts are usually carried by your retail "chain" parts suppliers and are intended to be sold to "this is your job", which is more concerned with price than quality or longevity. However, in my experiences, there are some aftermarket companies that take OEM parts to the next level of quality. The MOOG suspension components are a good example, they take for example a ball joint, reverse engineer the part and then recreate a replacement part that is of high quality. These products most of the time are equal to the OES portion price but give an outstanding lifetime warranty. Finally, there are many options to meet your car repair, service and budget needs without sacrificing overall quality