Parts retailers are drawing more attention to brands more than ever before. There is the strong desire to avoid "cheap Chinese crap" and only use German-made pieces. This is the wrong outlook and customers should be focused on the quality and reputation of the parts brands rather than where they were made. BMW produces very few components themselves - large metal components like engine blocks and complex composite pieces like the i3's carbon fiber chassis. BMW buys most of their parts from other sources, referred to in the industry as Tier 1 suppliers. Examples are Bosch, Continental, and Pierburg. And these parts may be made anywhere in the world, from Mexico to Turkey and even China. The computer or phone you're reading this on likely came from China - do you consider it a 'crappy' product?
Tier 1 suppliers may be allowed to sell the products to the general public through distributors. This depends on who owns the part design and what their contract is with BMW. BBS may produce wheels for BMW but cannot sell them because BMW owns the design. However, Bosch can sell a spark plug because it's their own intellectual property.
I have always considered there to be 4 groups of BMW parts suppliers: OE (BMW), OEM (Tier 1), aftermarket (not OEM), and performance aftermarket (improved aftermarket and not OEM). Recently, FCP Euro came up with new definitions but I wish they had left the original explanations alone. I believe credit for tiers in the BMW market goes to Vincent at BimmerZone and Doug at Turner Motorsport, with some additional input from me. FCP has confused things without really adding any benefit. I have added their explanations to my own below.
OE vs. OEM
OE (Original Equipment or Genuine BMW)
These are the EXACT parts you get from the parts counter at an authorized BMW dealership. Example: Oxygen Sensor, BMW Part # 11 78 1 735 499. These parts likely have a BMW logo somewhere on the part itself and usually come in BMW-marked packaging.
FCP calls these Genuine Parts/
FCP Original Equipment (OE) Parts
FCP separates Genuine and OE parts as distinct from each other. But isn't a Genuine part the "Original Equipment" for the vehicle? The car came with a BMW-branded serpentine belt as original equipment, not a Continental brand. Maybe it's my own rant but I think this muddies the waters too much.
OEM (Original Equipment Manufacturer)
OEM parts come from the same factory that makes your Original BMW parts, but they are boxed in their respective brands. BMW actually makes very few components themselves. Nearly the entire car consists of components and sub-assemblies sourced from various manufacturers or Tier-1 suppliers. (Example: Bosch Oxygen Sensor part #13231, which cross references to: BMW Part # 11 78 1 735 499). These parts are sold directly from the manufacturer to distributors, suppliers, or retailers and not through the BMW dealer network. This usually means savings for the end consumer while still having the same OE standards that the vehicle manufacturer specified. They are identical - a lot of times you can find where the OEM part has the BMW logo removed! In order to be labeled as an OEM part, it must meet the exact same design as the original part, regardless of where in the world it was manufactured. Any deviation from the original BMW spec is not considered OEM. In addition, in Germany for a part to be labeled "OEM" it must achieve German TUV certification.
Some OEMs may choose to produce a performance version of the original design. Technically speaking, these are no longer OEM parts but since they are coming from the original supplier you can be sure the quality is excellent and on par with the original. We generally refer to these as 'Performance Alternatives'.
At FCP this would be a part that comes from a Tier 1 supplier but the Genuine BMW part was sourced from someone else. So the manufacturer is an OEM but they did not supply this piece for BMW. FCP may have a technically valid point here. Ate has long been a Tier 1 supplier for BMW brake components but they did not manufacture the brake calipers used on F30 models. I would call them "an OEM supplier" without labeling the part OEM. What is more important - the reputation of the brand or the quality of part? I believe the reputation of the brand is what determines the quality of the part. FCP is trying to make a distinction that doesn't need making, in my opinion.
Aftermarket parts are produced by manufacturers that have no connection with BMW on that particular part. These are generally copied from OE parts but produced and sold for less cost than an OE/OEM. They are not necessarily inferior, unsafe, or poorly made. But since they have not achieved OEM or TUV status their quality is not guaranteed. In some cases, an aftermarket part may be superior to OEM (Zimmermann brake rotors) but it is rare.
This is a brand like Meyle HD. Meyle is not an OEM for BMW but they produce parts with decent quality. But then they took an extraordinary extra step - they improved on the OEM design! The HD engineers look for the weaknesses in the OEM design and come up with a way to make it better. If rear trailing arm bushings on the E36/E46 are too soft and wear out prematurely, they made a stiffer version that lasts longer yet is still comfortable to use on the street. Yes, it is likely made in China but in ten years of selling them it seems that Meyle HD produced a superior bushing. An OEM or aftermarket manufacturer who re-designs the products to be better is almost unheard of but this is often what we need as BMW owners!
Bottom line: ask your supplier for their opinion. But if they can't give you an honest answer then look elsewhere. Ask which brand has the highest return rate. If you show a little interest and trust his/her opinion you should get what you want. It's not all about the price.
"The bitterness of poor quality remains long after low pricing is forgotten," - Leon Cautillo, author.