During the Cold War, the term Communist Bloc (or Soviet Bloc) was used to refer to the Soviet Union and countries it either controlled or that were its allies in Central and Eastern Europe (Bulgaria, Czechoslovakia, East Germany, Hungary, Poland, Romania, and—until the early 1960s—Albania).
The label "Eastern Bloc" was also used to collectively denote member states of the Warsaw Pact (a Soviet-dominated military organisation) or the Comecon (an international economic organization of Communist states). Allies outside of Eastern Europe, such as Mongolia and often China, Cuba, Vietnam, Ethiopia, and North Korea were sometimes included in the term Eastern Bloc as well.
The terms Eastern Bloc and Soviet Union are sometimes confused. Although the Soviet Union had much political and economic influence over its Eastern Bloc possessions, the other countries in the Eastern Bloc were never constituent republics of the Soviet Union.
Similarly, the Stalinist Albanian government also came to power independently of the Red Army as a consequence of Albanian partisan resistance during World War II. Albania broke with the Soviet Union in the early 1960s as a result of the Sino-Soviet split, aligning itself instead with the People's Republic of China and its anti-revisionist stance.
Romania was a bit of an anomaly, since the Communist Party came into power with the help of the Soviet Union. However, after Nicolae Ceauşescu came to power, he pursued a policy more independent of the Soviet Union. For example, Romania was the only country in the Eastern Bloc to condemn the 1968 invasion of Czechoslovakia. Though Romania did not break with the USSR as a result of the Sino-Soviet split, it nevertheless maintained good relations with China. Similarly, the Russian language was taught less in schools, Romania entered into foreign relations with several Western countries because of this independent line, and on a lesser note, the Bucharest Metro did not use the cars that were typical of Eastern Bloc metro systems. This independent line, which promoted Ceauşescu's megalomaniac visions, also resulted in a revolution against the Communist government and the execution of the Ceauşescus, as opposed to the usurption of power in the rest of the Eastern Bloc.
Even before this period, all the countries in the Warsaw Pact did not always act as a unified bloc. For instance, the 1968 invasion of Czechoslovakia was condemned by Romania, which refused to take part in it.