There is no single definition of what the West is, so the list of countries changes depending on context. The different contexts are outlined in this Wikipedia article.
To sum it up (quotes from WP):
Cultural definition – From a cultural and sociological approach the Western world is defined as including all cultures that are directly derived from and influenced by European cultures. This is probably the broadest definition.
Political definition – Countries of the Western world are generally considered to share certain fundamental political ideologies, including those of liberal democracy, the rule of law, human rights, equality.
Taking: (1) European culture; (2) very high human development; and (3) liberal democratic principles, we get these countries:
Here are these countries listed in alphabetical order:
- Czech Republic
- New Zealand
- San Marino
- United Kingdom
- United States
- Vatican City
It is debatable whether Israel has “European culture”, though the centuries of European influence are undisputed. Many would also assert that Israel does not truly embody liberal democratic principles. Therefore the status of Israel on this list is debatable.
Poland and the Baltic States are European in culture, but distinct from Western Europe, albeit not as much as Russia or other East Slavic countries.