Debt is only important as a percentage of GDP. The actual debt figure is fairly irrelevant. It is when you stack the debt figure against the GDP that you see how good / bad the debt load of a country is.

The trouble Europe has is that a number of member states are drowning in debt. Their debt greatly exceeds GDP and it is getting worse.. for a country like Italy this is recoverable as long as the markets believe they can pay it back! As soon as the markets stop believing their debt interest will stay above 7%, they will unable to maintain their debt and will probably go under as they are too big to bail out.

This is where UK and the US differ. There is a strong belief in the markets that they can pay their debt back just fine. The interest on their debt is about 2% and everything is manageable.

At least this is how I understand it.