European countries
A formal, somewhat literary term for the nations of Europe, often used in news or political contexts.
European countries are strengthening cooperation on immigration issues.
I plan to visit various European countries.
More common and neutral in everyday speech; 欧州諸国 is more formal and often used in written or official contexts.
Compound of 欧州 (Europe) and 諸国 (various countries). 欧州 is an abbreviation of 欧羅巴 (Europe) combined with 州 (continent).