Toyota Repair: OEM parts, michelin tires, qc standards

Question
Hi ,

What is the difference between OEM parts and Genuine parts , apart from being 50% cheaper ?
Thanks and keep up the good work
Louis

Answer
The difference can be very small or very large for any particular part, the biggest factor is quality control, the OEM parts in general have stricter QC standards than aftermarket parts so there is a bigger chance of getting a part that may have a defect, most aftermarket parts have a very good warranty meaning that the alternator you bought that was assembled in China, at half the price of a factory reman unit  may fail soon and you may get stuck someplace, they will just give you another one under their guarantee but you are faced with the inconvenience of having to be towed and returning the part, they cover only the part and nothing else, a dealer installed OEM part is warranted for the part and the labor and in most cases towing costs.   
It's kind of like buying tires at a discount tire place like Costco, sure they are Michelin tires but few people realize that these are the tires that are rejected by the major tire retailers, not that they are bad or unsafe, they just don't meet their standards.