Sejm different from Senate of Poland
The Sejm (English:  "same", Polish: [sɛjm] (listen)), officially known as the Sejm of the Republic of Poland (Polish: Sejm Rzeczypospolitej Polskiej), is the lower house of the bicameral parliament of Poland.
The Sejm has been the highest governing body of the Third Polish Republic since the transition of government in 1989. Along with the upper house of parliament, the Senate, it forms the national legislature in Poland known as National Assembly (Polish: Zgromadzenie Narodowe). The Sejm is composed of 460 deputies (singular deputowany or poseł – "envoy") elected every four years by a universal ballot. The Sejm is presided over by a speaker called the "Marshal of the Sejm" (Marszałek Sejmu).
In the Kingdom of Poland, the term Sejm referred to an entire two-chamber parliament, comprising the Chamber of Deputies (Izba Poselska), the Senate and the King. It was thus a three-estate parliament. The 1573 Henrician Articles strengthened the assembly's jurisdiction, making Poland a constitutional elective monarchy. Since the Second Polish Republic (1918–1939), Sejm has only referred to the lower house of parliament.Second Polish Republic
After the First World War and re-establishment of Polish independence, the convocation of parliament, under the democratic electoral law of 1918, became an enduring symbol of the new state's wish to demonstrate and establish continuity with the 300-year Polish parliamentary traditions established before the time of the partitions. Maciej Rataj emphatically paid tribute to this with the phrase: "There is Poland there, and so is the Sejm".
During the interwar period of Poland's independence, the first Legislative Sejm of 1919, a Constituent Assembly, passed the Small Constitution of 1919, which introduced a parliamentary republic and proclaimed the principle of the Sejm's sovereignty. This was then strengthened, in 1921, by the March Constitution, one of the most democratic European constitutions enacted after the end of World War I. The constitution established a political system which was based on Montesquieu's doctrine of separation of powers, and which restored the bicameral Sejm consisting of a chamber of deputies (to which alone the name of "Sejm" was from then on applied) and the Senate. In 1919, Roza Pomerantz-Meltzer, a member of the Zionist party, became the first woman ever elected to the Sejm.The legal content of the March Constitution allowed for Sejm supremacy in the system of state institutions at the expense of the executive powers, thus creating a parliamentary republic out of the Polish state. An attempt to strengthen executive powers in 1926 (through the August Amendment) proved too limited and largely failed in helping avoid legislative grid-lock which had ensued as a result of too-great parliamentary power in a state which had numerous diametrically-opposed political parties sitting in its legislature. In 1935, the parliamentary republic was weakened further when, by way of, Józef Piłsudski's May Coup, the president was forced to sign the April Constitution of 1935, an act through which the head of state assumed the dominant position in legislating for the state and the Senate increased its power at the expense of the Sejm.