The countries which have high birth rate are called the under-developed countries. Such countries are distinguished by poverty, beggars and poor villagers. They lack its own factories, power and light, smooth roads, hospitals and schools.
I'm pretty sure all the countries in Europe are pretty much developed in comparison to some of the countries in Africa, Asia or South America, for instance. All the countries in Europe have electricity everywhere, clean water, healthcare and people rarely die from curable diseases that are spread in other continents or starvation.
It's a very subjective matter as some European countries are less developed than others, in certain areas at least. For example Russia might not be as developed in human rights and freedom of speech in comparison to Portugal but it's a lot more industrialized and you could say in that area it's very developed.
If you look deeper into that you could say that the countries that used to be communist in the period 1945–1989 are less economically developed than the rest of Europe. Again if you look even deeper, say within the EU, you could say the countries that joined in the 21st century are less developed than the old founding countries.
If you judge a country's development level purely by statistics or stuff like GDP then the answer is very easy to Google but let me help you it's mostly former Soviet countries outside the EU such as Ukraine, Moldova and Georgia or countries which experienced war or unrest recently such as Bosnia & Herzegovina, The Former Yugoslav Republic of Macedonia and Kosovo.