How are they different? I have done some corporate CDS valuations but I want to know how to value sovereign CDS. Thanks!
For pricing a hard currency denominated CDS, it does not matter whether the reference entiry is corporate, sovereign, agency, muni, etc. The calculations are the same. Do try to use market conventions for your recovery assumptions - many people assume 40% for corporates, 25% for emerging markets sovereigns.
If the CDS is in local currency, then you should include a "quanto factor" in your calculation. It is your assumption of how the local currency would be affected if the sovereign defaults on its (hard-currency) debt.
But if by valuing you meant not pricing, but something similar to Altman's Z-score, Moody's KMV, etc - estimating the physical probability of default by looking at various ratios from financial statements - then generally this can be done for corporates with publicly traded stock, so financial statements are available; and cannot be done for sovereigns.