<Li> Oil Service Company: </Li> <P> A company that provides products and / or services to the oil and gas industry . Usually a combination of labor, equipment, and / or other support services . Examples include Baker Hughes, Haliburton, and Schlumberger . </P> <Ul> <Li> Oil Equipment Manufacturer: </Li> </Ul> <Li> Oil Equipment Manufacturer: </Li>

What is the meaning of downstream and upstream