The 1905 Russian Revolution was a wave of mass political and social unrest that spread through vast areas of the Russian Empire. Some of it was directed against the government, while some was undirected. It included terrorism, worker strikes, peasant unrest, and military mutinies. It led to the establishment of limited constitutional monarchy, the State Duma of the Russian Empire, the multi-party system, and the Russian Constitution of 1906.
The Russian Revolution is the collective term for a series of revolutions in Russia in 1917, which destroyed the Tsarist autocracy and led to the creation of the Soviet Union. The Tsar was deposed and replaced by a provisional government in the first revolution of February 1917 (March in the Gregorian calendar; the older Julian calendar was in use in Russia at the time). In the second revolution, during October, the Provisional Government was removed and replaced with a Bolshevik (Communist) government.
The February Revolution (March 1917) was a revolution focused around Petrograd (now St. Petersburg). In the chaos, members of the Imperial parliament or Duma assumed control of the country, forming the Russian Provisional Government. The army leadership felt they did not have the means to suppress the revolution and Tsar Nicholas II of Russia, the last Tsar of Russia, abdicated.
The Soviets (workers' councils), which were led by more radical socialist factions, initially permitted the Provisional Government to rule, but insisted on a prerogative to influence the government and control various militias. The February Revolution took place in the context of heavy military setbacks during the First World War, which left much of the army in a state of mutiny.