If the two do the same thing, is not always the same
https://www.bbc.com/news/world-europe-18328859Kosovo unilaterally declared independence from Serbia in February 2008, after years of strained relations between its Serb and mainly Albanian inhabitants.
It has been recognised by the United States and major European Union countries, but Serbia, backed by its powerful ally Russia, refuses to do so, as do most ethnic Serbs inside Kosovo.
And it was without any referendum but with a massacre.
Compare with Crimea...