What is the difference between sovereign debt and national/government debt?

Thanks in advance!
A Sovereign debt is one that is guaranteed by a government, whereas national/government debt is incurred by that government
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Feebs, thank you very much for your reply. I must read sth about it because I don't get it.
I've found in the dictionary (Longman Business English Dictionary):
sovereign debt - money owed by a government, rather than a company or person.
national debt - money borrowed and still owed by a country
public debt - money owed by a local or national government.

All is similar for me.
Here's another fuller definition:
Sovereign - Refers to a debt security issued by a government other than the United States. It is often believed that the issuing government via its treasury will fully back the payment of interest and principal in a timely manner. Sometimes, that backing is insufficient and a default occurs.
At times of default, there are distinctions. Sometimes, there is a political upheaval and the new regime repudiates the former's obligations. At other times, there can be a lack of specified reserves to honor the obligations but a workout or restructuring of the payment schedule is agreed, bilaterally.

And another reference:

http://www.investopedia.com/terms/s/sovereignbond.asp .

National and Public debt relates to money raised by a government by borrowing in order to balance its internal budgets.
Thanks for your clarifications. I'm slowly beginning to understand it.
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