OEM - original equipment manufactuer
clone - a knock off of an OEM
Component - a company with their own R&D, design and distribution. THey have customer service and produce high quality equipment. Quite often their high end equipment is better that OEM equipment.

If you are looking for component (highly recommended) go for a SMT, Alpha, or my component of choice, Ashton. I have the new MS-5 driver and it is AWESOME.