It's really hard to compare both dev markets. In Europe, salaries varies a lot depending on the country. There is Switzerland where average dev can earn up to 120k CHF (~ $130k) [1], and on the other hand we have Germany with average of 60k EUR (~ $70k) [2]. The UK is rather similar: 60k GBP (~ $82k) [3]. To have a perspective, we can also add Poland to the list: 240 000 PLN (~ $61k) [4]. As you can see, it's not that simple, especially when you take into consideration the tax rates and costs of living in each country.

Annotation: Average gross annual salaries taken from the job boards that require salary brackets: [1] https://swissdevjobs.ch [2] https://germantechjobs.de/en [3] https://devitjobs.uk [4] https://nofluffjobs.com