In a common market, labor costs will look fairly similar across areas. Sure, there will be some places with differing skill levels, different mixes of industry, and different levels of urbanization, thus leading to somewhat higher or lower labor costs. But over time, workers from lower-pay areas will tend to relocate to higher-pay areas and employers in higher-pay areas will tend to relocate to lower-pay areas. Thus, it's interesting that the European Union continues to show large gaps in hourly labor costs.
Here are some figures just released by Eurostat (March 31, 2021) on labor costs across countries. As you can see, hourly labor costs are up around €40/hour in Denmark, Luxembourg, and Belgium, but €10/hour or below in some countries of eastern Europe like Poland or the Baltic states like Lithuania. (For comparison, a euro is at present worth about $1.17 in US dollars. Norway and Iceland are not part of the European Union, but they are part of a broader grouping called the European Economic Area.)
For comparison, here are some recent figures from the US Census Bureau on average employer costs per hour across the 10 Census "divisions." Yes, there are substantial differences between, say, the Pacific or New England divisions and the East South Central or West South Central divisions. But the United States is much more of a unified market than the European Union, both in wage levels and in the way non-wage labor costs are structured, and so the gaps are much smaller.