More strict version of socialism. E.g. private business was flat-out outlawed in USSR until the very end. Other eastern bloc countries had more lax rules. On t

More strict version of socialism. E.g. private business was flat-out outlawed in USSR until the very end. Other eastern bloc countries had more lax rules. On top of that, USSR was actively trying to incorporate newly acquired territories and assimilate non-Russian people to build the Soviet Man. Significant part of population wasn't very happy about it. Meanwhile satellite countries were busy building nation states and had less internal struggle. IIRC, Soviet budget was much more military-oriented as well. More money towards budding regimes in Africa, Asia and South America too. Meanwhile satellite countries in eastern bloc were neutral or even received some resources from Moscow.