The Baltic Republics vs. the rest of the USSR. Just FYI, since I assume you're not very familiar with these countries: this kind of lumping together the so-called "Baltic Republics" with the "USSR" is generally very offensive to Estonians, Lithuanians and Latvians, who have nothing to do ethnically or culturally with Russia and generally view the Soviet era as very dark times. Estonia, Latvia and Lithuania were invad…
Estonia, Latvia and Lithuania were parts of Russia for 300 years with small omissions. It is longer than the time of existence of the United States. So they have a lot cultural and ethnical similarity with Russia. But yes, they try to ignore it officially.
The only thing Latvians share with Russia is the border unfortunately.
There are no major cultural or ethnic similarities.
The language is so different it doesn't even belong to the same branch in the language tree. (compared to family of Slavic languages - Ukrainian, Belarusian, Slovak, Polish, Czech, etc)
Latvians do not want anything to do with Russia or it's culture or it's politics.
The same is true for Estonia and Lithuania.