Answer:
The Bolsheviks and Mensheviks were political factions within the group that was known as the Russian Social-Democratic Worker's Party. They aimed to bring about a social revolution following the theories of Karl Marx.
The Russian Revolution of 1905 was caused when the Russian people were frustrated with the repeated failures of the Tsar, including the humiliation of the Russo-Japanese War of 1905. Tsar Nicholas II responded to this mass social disruption with reforms such as the October Manifesto and the State Duma.
Vladimir Lenin was the leader of the Bolshevik Party, and after the Bolshevik Revolution ousted the provisional government, he became the first and founding head of Soviet Russia, and later the Soviet Union. Ideologically, the Bolshevik Party (and Lenin) were Marxists, however, Lenin altered Karl Marx's original communist philosophy and created Marxist Leninism, which became the ideology of the Soviet Union.
The October Revolution, also known as the Bolshevik Revolution, is the revolt in which the Bolshevik Part, lead by Lenin, overthrew the provisional government set up after the abdication of Tsar Nicholas II. The Revolution was a nearly bloodless coup d'état. The rise of the Bolsheviks and their newly gained control of the government made Russia a communist country.