Men shevicks, these socialist thought that contradictions in Russia were not ripe for socialist revolution due to Lack of Large industrial working class and industrial sector, So they felt that capitalist should led the revolution against feudalism in the country and later on workers will be able to gain experience for Later socialist revolution.
Bolsheviks, these are extreme socialist, this group was led by V.J. Lenin.
The Bolshevik criticized the men shevicks for treating Marxism as a dogma (doctrine) which means theories said by Marx should not be changed VI Lenin argued that Karl-max once said. In time of revolution there must be flexibility.
This group believed that the capitalist could not play a progressive ant feudal lord in Russia because the capitalist asked with the ruling class under Tsa Nicholaus II to oppress, humiliateand exploit the normal Russians (Majority) hence Lenin and his group believed that the revolution should be Learn by the party of the working class which must make alliance with the poor peasant.