Wereboar
"Very insistent that they are not Eastern European, preferring instead to link themselves to Catholic culture (all countries in this region are majority-Catholic)". Not really. Only Poland, Hungary and Slovakia have Catholic majority (and culture of these countries are heavily influenced by the West, partially because parts of these countries were technically Prussia/Germany and Austro-Hungary in 19th century. It is even more pronounced in the case of Czech Republic (that is also the most non-religious country in Europe for variety of causes). Almost all other countries (Romania, Bulgaria, Bosnia, Serbia, Montenegro etc.) have Orthodox majority.
The division is quite simple, really. Slavic countries with significant influence of the Western European culture (Poland, Czech Republic, Slovakia, Hungary, Romania) define themselves as 'Central Europe' (because they are not really Western and not really Eastern), those that are predominantly Ruthenian in origin and use Cyryllic alphabet (Russia, Belarus, Ukraine) are 'Eastern Europe' and countries with heavy southern influence (Italian in the west, Turkish/Greek to the east) such as Slovenia, Croatia, Serbia, Montenegro or Bulgaria define themselves as 'Southern Europe'. And there are, of course, Baltic States (Lithuania, Latvia, Estonia) where the first one considers itself a Central European country, while the two latter think of themselves as predominantly Western states (and for a good reason as their culture is predominantly Scandinavian/Germanic).
The "Ukrainian" part was 95% written by a Russian Nazi, which is a bit ironic.