The national or government debt is a combination of both internal and external debt. The external debt is referred to as Sovereign Debt. Sovereign Debt refers to bonds issued by a nation’s government in a foreign currency and sold to foreign investors.
A liability is a debt. It is an obligation that arises during the course of business and represents a third-party claim on the company's assets. A liability can arise in a number of different ways. It can be a type of borrowing or a promise to pay later.