Maoism argues that rural peasants should play a key role in communist revolutions. This wasn't the case in Russia because the agricultural population didn't play any significant role since the communist party pretty much existed in the cities and was backed by industry workers.
Lenin believed the party was supposed to act as a vanguard of the people. That it should instruct them on the revolution, its purposes and leading them with their best interest in mind.
Mao, on the other hand, believed that people naturally revolutionary and that we should learn from the people.