These leaders believe that communism could change the power structure and the economic system known as capitalism.
The system notably failed in almost every country in which it was implemented, save for a few that learned to ignore communist economics altogether China.
America's Founding Fathers included the promotion of the general welfare in the Constitution to balance these flaws.
Economic output is distributed according to the needs of the people.
This Khan Academy explains what a communist system is.
Planned or controlled economic systems are usually some form or variant of Socialism, but certainly not capitalism.