Bolshevik is a translation of "majority group" and Menshevik is a translation of "minority group".
Lenin wanted a small group of professional revolutionaries working to undermine the Tsarist system.
He argued that the bourgeois and socialist revolutions of Marxist theory could happen simultaneously.
Martov disagreed and argued that the bourgeois stage of Marxist theory must be allowed to run its course.
In the meantime, Martov perceived the role of the SDs to be one of educating workers and increasing party membership as widely as possible.
The majority of the party backed Lenin, the minority of the party backed Martov.
Martov was prepared to work within a democratic system.
Lenin wanted nothing to do with liberal democracy and aimed to overthrow both tsarism and democracy at the same time.
The SD movement was weakened because of the split between the Bolsheviks and Mensheviks which had existed since 1903.
They disagreed about how to respond to the creation of the Duma.
The Mensheviks were prepared to stand for Duma elections as they saw it as part of the democratic phase of Marxist historical development.
The Bolsheviks boycotted the first two Duma elections as they only saw revolution as the way forward.
When Stolypin changed the voting system in 1907, the Mensheviks refused to participate in Duma elections in protest.
The Bolsheviks saw an opportunity to gain support from working class voters, decided to stand in the elections for the Third and Fourth Dumas in 1907 and 1912.