Marxism is very different from Maosim, Stalinism or Leninism. Basically Marxism has never really been successfully implemented.
Capitalism = a few who are incredibly rich, and the majority are poor
Marxism = no one is incredibly rich, majority is decently wealthy (he thought that the vast amount of wealth the top 1% had could be evenly distributed to everyone)
In practice communism (Leninism/Stalinism/Maoism) = a dictatorship where a handful of people control the wealth and power, and majority is poor.
So that’s the difference. Marx never intended communism to be autocratic but it always turn into a personality-cult led dictatorship in practice. Marx had great ideas but only in theory. It’s that theory that got Chinese people interested in communism. Mao promised wealth for everyone – at a time when most Chinese were illiterate and impoverished. And in a way he did, after inventing Simplified Chinese most Chinese could now read and write, and all Chinese had free education, housing and healthcare. But compared to American style capitalism the average Chinese was still poor, and Mao was basically a dictator.
In a Marxist system, Mao would not be a dictator and the average middle class Chinese would be much more wealthier than they actually were during the 50s/60s/70s. But its impossible to implement because humans are greedy and humans want power and absolute power corrupts absolutely – which Mao found out. During the 1950s Mao actually cared about the welfare of the people, but as time went on during the 60s/70s he got corrupted by power and refused to relinquish it.