Ukrainian and Russian both belong to the Slavic language family — languages considered difficult for native English speakers because of their different alphabet (Russian, Ukrainian, Bulgarian, Serbian, and Macedonian), complex system of endings, perfective and imperfective verb forms, unpredictable accents within words, difficult pronunciation, and different mindset from romance or germanic languages. That being said, the hardest part is simply getting started. After that it's just like learning any foreign language. As Mike said, Ukrainian and Russian are used roughly equally across Ukraine. While the official state language of Ukraine is Ukrainian, the preferred spoken language in most cities of southern, eastern, and northern Ukraine is Russian.

We, russian speakers, understand ukrainian and can master it very quickly if we want.

http://en.wikipedia.org/wiki/Slavic_languages Of course, there is a difference! As for example, between Uzbek and Azerbaijani. What do you think, what's the difference between a red apple and green apple? :))