What caused the Russian civil war?

The imbalance, which was caused by aristocracy in a shortest form. Not really differ from French Revolution in causes. The difference between those two is French was made by burgoise against aristocracy, in Russia it was farmers, villagers, countrymen etc.

The Russian Civil War must be distinguished from the Russian Revolutions of 1917. They are not the same; therefore their causes are not the same. The Civil War was caused because Lenin and his Bolsheviks took over the government from the Russian Provisional Government and announced that they were now in power. The Bolshevik party did not represent the population of Russia. Many people, including some members of the military, the former government and aristocracy were unhappy with the Bolshevik take over because they did not agree with all of its principles. A large portion of this opposition consisted of the Russian Army under the leadership of generals who were opposed to the Bolsheviks.

The Bolsheviks did not have a legitimate claim to the right to govern, because they were a small proportion of the populace; therefore many people opposed their take over. This opposition coalesced into a force determined to oust the Bolsheviks and return the government to the Provisional Government. Lenin had created an armed force called the Red Guard, which became the Red Army. The opposition forces became known as the White Army and White Russians. The two sides could never come to an agreement on which side should rule and the Russian Civil War was on.