I am certainly NO expert on the Balkans or
Ukraine. Most of what I knew was confirmed in my brief look at several websites.
ONE key difference is that the former country of Yugoslavia was, to me, destined for break up as it was a collection of many different and rather divergent and diverse ethnic groups. The dissolution of Yugoslavia after the death of Tito was inevitable.
Ukraine is different in that it has (it seems to me) mostly those who call themselves Ukrainian and then significant numbers of Russian immigrants who live in Ukrainian territories. As with many nations, I am sure there are small enclaves of other groups and ethnicities. I am not aware of another significant minority population in
Ukraine.
https://www.britannica.com/place/Ukraine/PeopleThere were reports of much discrimination and worse by the majority groups in many areas of then Yugoslavia. How much of that was "propaganda" I do not know.
My recollection of history is that Yugoslavia was "put together" after WW2 and the break up of the Austrian-Hungarian Empire.
https://en.wikipedia.org/wiki/Breakup_of_YugoslaviaObviously the history of the region is very complex:
https://en.wikipedia.org/wiki/YugoslaviaDue to its complex history, there was a great sense of many ethnic groups yearning to have its own lands and to be free of oppressors and overlords. THAT, to me, is another KEY difference between
Ukraine and the Balkans and Yugoslavia.
A key question/issue for the world going forward is how many nations are needed to allow peoples those freedoms and their ability to determine their destiny? How to respect the rights of a small minority without breaking up larger nations? Those are the continuing questions.
Crimea is a good example of ethnic Russians moving there in the past 200 or less years, to man the former Soviet and Russian naval base(s) there. There were likely some ethnic Russians there before 1917. Crimea also has lots of desirable vacation lands and beaches and such, as well a lands to grow grapes and other crops. I am sure there is lots of money from oligarchs there buying such desirable places.
I met a young man who is from
Ukraine and he was proudly Ukrainian. He is blonde and blue eyed and appeared to me to be Scandinavian; that may be the Viking influence. He is a very bright person and was an exchange student in my class for several month (about 15 years ago). He got the attention of the entire class when he spoke of his people being SLAVES. [As a side note, he really enjoyed the cupcakes my wife and I gave him at a going away celebration on his last day in my class. He took THREE (and asked for #3. "Of course, Vlad..!" I said.) Other students took one.]
Another KEY difference is that Putin is using minority status of some Russians to justify his land grab and his desire to install governments friendly to Russia on his borders. He does not like it that many nations of Eastern Europe do not want to part of his Russian Sphere of influence. {This is my first edit of this long post.} Kosovo was not formed to please a large power in the region, another KEY difference.