The two terms are not synonymous and their properties are not coterminous. The EU countries in the current imbroglio are locked in a completely different paradigm than sovereign currency issuers ("SCIs") as they have funding requirements independent of fiscal debt issuance.
This is why the arguments concerning the U.S. and to a greater extent the U.K. with regards to "contagion risk" are exaggerated.
National Debt to countries facing liquidity issues is a real risk as liabilities must be paid with non-issued currency. With SCIs, National Debt serves as an interest rate management vehicle. Taxation in countries facing liquidity issues actually raises the necessary currency to pay external obligations. With SCIs, Taxation serves as an aggregate demand regulator.
That the Eunuch class has not seen this goes beyond mere negligence. There is no-one among them that woudld drink the professional equivalent of Hemlock.