Can you hear the difference between Serbo-Croatian and Bulgarian or Russian and Belarusian or Slovak and Czech?  :)

I could try. :) The pronunciation in Czech sounds noble and soft, while Slovak on the opposite sounds rougher and archaic. Between Bulgarian and Serbo-Croatian there's even a bigger difference, because Bulgarian vocabulary is influenced a lot by non-Slavic languages (Turkic and native Balkan). I can't explain the exact difference, but Bulgarian sounds generally different from any other Slavic language I've heard.

I read somewhere that Belorussian vocabulary is influenced by Baltic languages, while the pronunciation is similar, if not identical, to the Russian. Can you explain me the difference, from your perspective, between Belorussian and Russian, and in what relation is the Belorussian language with Baltic languages.