Russian and Ukrainian are related but are two separate languages since the Ukrainian language sounds softer than Russian and uses a slightly larger alphabet. Ukrainian has some different grammar rules - for example, an additional future tense, an additional past tense, a way of using adverbs that would be strange in Russian, and some other different syntax features. It has some sounds that don’t exist in standard Russian, like the h in hryvnia and the yi in Ukrayina, the name of the country; also, the e sound is used in Ukrainian much more frequently while in Russian it would be ye.
When Russians start playing the bandura then maybe I’ll consider them the same people: https://www.youtube.com/watch?v=zJeBgeMcuyc
https://www.youtube.com/watch?v=1KAHyuVjjmg
The Russian commies tried to murder every single person who played the bandura in the 1920s and 1930s.
Even the Ukrainians are blown away when someone can play it well: https://www.youtube.com/watch?v=cdmp99xXBgU
Dyakuyu
The 'language vs dialect' issue has no solution within the science, it's a political thing. There are dialects in Russian which differ grammatically from the literary Russian, e.g. with the definite article.
The 'Russian commies' thing is a manipulation since the ethnic Ukrainians of the Soviet era were equally Communist as the Russians.