Country Debt to GDP Ratios

I certainly don't understand the implications of external vs. public debt and ratios to GDP but the below data visualization via Many-eyes shows the following: 

• UK has an external debt ratio 5 times larger than its public debt ratio.
• Spain has an external debt ratio 3 times larger than its public debt ratio.
• Japan has a public debt ratio about 5 times more than its external debt ratio.

External debt (or foreign debt) is that part of the total debt in a country that is owed to creditors outside the country. 


Public debt (also known as government debt, national debt, sovereign debt) is money (or credit) owed by a central government.