What's the differences between the national corporation and private company?

i am encountering to find a job,i want to know more about these differences,if you give me some advices ,thank you very much!
What's the differences between the national corporation and private company?
A national corporation does business throughout a country. It can be publicly or privately held. A private company is privately held, not owned by stockholders. There's really no way to compare the two.
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