What are OEM Parts?
OEM arguably stands for Original Equipment by the Manufacturer. With OEM parts, you know they're going to fit and perform like the factory intended or requires. Aftermarket parts may sometimes offer advantages, but generally, over time, vehicles with original equipment will be worth more and have a better resale than one built up with aftermarket parts.
OEM. It's not a replacement part, it's original equipment, and with that comes a certain measure of security and certainty that what you're getting is the standard used to measure anything else.
About OEM Parts...
OEM is a term that used to be used mainly by tradesmen in the industry to refer to genuine parts from the original manufacturer of a vehicle. Obviously, there are other ways people refer to genuine parts from the factory. OEM parts may be refered to as original, factory, or Original Equipment by the Manufacturer. This term has become more common over the years.
So what's the difference between OEM parts and aftermarket parts? OEM parts, being original equipment are not replacement parts so to speak because they are the same part the vehicle came with when it was brand new. Original Equipment.