First of all, Marxism aims at attaining a sort of equanimity with regard to the people especially between the rich and the poor. It has firm roots in history and is based on the history of society in the past Marxism lays its ideologies for the uplift of the society.
It is important to understand here that the Marxist theory strongly believes in the implementation of its theoretical interpretations and also expects practical applicability of those theories on their own accord. This actually is the main difference between Marxism and neo-Marxism, or any other system of political thought for that matter. Many political pundits believe that Marxism is the foundation for the formation of several other political thoughts such as Leninism, Socialism and other economic systems and thoughts including Neo-Marxism.
Neo-Marxism on the other hand is said to incorporate several ideas and philosophies from Marxism including the concept of critical theory, psychoanalysis and other related ideologies. Some of the examples of Neo-Marxist theories are Weberian sociology and Herbert Marcuse theories.