Polish People's Republic
The Polish People's Republic (, ) was a state in Central Europe that existed from 1947 to 1989, and the predecessor of the modern democratic Republic of Poland. With a population of approximately 37.9 million inhabitants near the end of its existence, it was the most populous state of the Eastern Bloc after the Soviet Union. Having a unitary Marxist–Leninist communist government, it was also one of the main signatories of the Warsaw Pact. The official capital since 1947 and largest city was Warsaw, followed by industrial Łódź and cultural Kraków.
Congress Poland
The Kingdom of Poland, informally known as Congress Poland or Russian Poland, was created in 1815 by the Congress of Vienna as a sovereign state of the Russian partition of Poland. Connected until 1832 by personal union with the Russian Empire under the Constitution of the Kingdom of Poland, it was gradually thereafter integrated politically into Russia over the course of the 19th century, made an official part of the Russian Empire in 1867, and finally replaced during World War I by the Central Powers in 1915 with the nominal Regency Kingdom of Poland.