What is the difference between factory new, aftermarket new, remanufactured, and used parts?

Factory New: an abbreviation for factory-new parts is OE (Original Equipment) generally is what the vehicle has been assembled with Aftermarket New: abbreviation OEM (Original Equipment Manufacturer) normally the producer of the parts supplied to the car manufacturer Remanufactured: are substandard copies or duplicates of the original parts Used Parts: are parts generally from vehicle salvage yards.