@Roman, you forget central Ukraine. Central Ukrainians are different than both east Ukrainians and West Ukrainians. Western Ukrainians were more influenced by Poles, Catholicism and Banderism. Central Ukrainians have a different nationalist history and actually had conflicts with western Ukrainian nationalist organizations. For example, central Ukrainians consider western Ukrainians traitors in the regard that they are more tolerant towards Catholicism and adopted Greco-Catholicism. The Bandera OUN also killed off central Ukrainian nationalist leaders like Jurij Horodianyn-Lisowski. 

 Some information and a photo of Jurij Horodianyn-Lisowski