You can search here or on google, wikipedia, etc.
Basically OEM means Original Equipment Manufacturer. Ford is an OEM. They buy from thousands of suppliers, who may be able to advertise they are "OEM Suppliers". Many OEM's specify in the contract that they cannot be referred to in any way. You might make ball joints for Ford, but you cannot ever mention that in any advertising. But you can still claim to be an OEM supplier, just no specifics.
So, what does being an OEM supplier really mean today? Nothing. Anyone can claim it and someone half the world away will never be forced to prove it.
And virtually all OEM contracts prevent the supplier from competing with or selling themselves the product they provide the OEM. A simple item such as a fan belt for Ford, let's say. Goodyear may make a particular fan belt for Ford. If you go to your local Ford dealer and buy that fan belt with the Ford logo and part number you are said to be buying an "OEM part".
You can go to an auto parts store and buy the same exact belt, but with the Goodyear number and logo and pay half the price, but you do not have the assurance it is a genuine OEM part. But Goodyear cannot put the Ford logo on the belt or the package. They can't tell you they make that belt for Ford. But, they can claim to be, honestly, an "OEM supplier."
Now those guys elsewhere in the world who make such claims. Notice I say claims, not always facts. The kung fu frito factory may make screws for Apple. They might also make cheap MP3's. And, they might claim to be OEM. They may even claim to be an OEM supplier to Apple. Which tey are, but not of electronics, but rather of screws. But they can still make the claim.
So, as greedyboy says, it's still fakes.