> The 'dialectical' approach to communism has meant slowly discarding almost everything which makes an economy communist.

The dialectical approach is the traditional approach, invented by Marx and added to by Engels and others, which they used to explain pretty much everything. It's not something invented by Deng Xaioping. It is in fact the essence of Marx's philosophy.

In a nutshell, the dialectic is an explanation for the evolution of society that looks at the systems by which society produces what it needs, i.e. "modes of production," and how contradictions in these modes of production are resolved through the creation of new modes. Hegel used the dialectical framework to describe the evolution of ideas, but Marx turned it upside down and argued that ideas were a consequence of the material conditions of life, the basis of which is the mode of production.

The classic example of Marx's dialectical thinking is his analysis in The Communist Manifesto that capitalism "produced its own gravediggers," the industrial proletariat. The proletariat would overthrow capitalism, but existed because of capitalism. The contradictions in the capitalist system caused the creation of an entire class of people which would eventually overthrow it and create a socialist society, and then a communist society. In other words, communism could never exist without capitalism having existed first, because the social class which would create communism would not have existed unless capitalism had created it.

Marx, followed by others including Lenin and Stalin, insisted that the full development of the productive forces was a necessary precursor to communism. He elaborated on this in the Critique of the Gotha Program, in which he advocated a different distribution of resources than in a full communist society -- some people would get more than others, according to their contribution to society rather than their need. At a later time, the productive forces would be developed to the point that they could provide enough wealth to distribute to everyone according to need, regardless of their contribution to society. (It's not unlike the arguments of some basic income proponents -- automation (productive forces) has created a society in which there is enough wealth to spread around to everyone, regardless of whether or not they have jobs.)

Similarly, the Soviet Union initially instructed the Chinese Communist Party to cooperate with the KMT in the 1920s, because they believed that full development of productive forces, under a capitalist regime, was a necessary precursor to communism. Not helpful, or merely good to have, but necessary according to Marx's dialectical philosophy.

The reason Marxism and Maoism are distinguished from each other is that Mao rejected that view, which was originally formulated by Marx, and advocated that communism be built by rural peasants rather than the industrial proletariat. Deng's ideology was closer to orthodox Marxism than Mao's was, in many ways. Deng argued that Mao tried to move too fast and skip the stages of social evolution that were necessary preconditions for communism, namely a thriving capitalist economy. If you want to redistribute wealth, you have to create it first. Deng argued that a market economy was the best way to do that, and that some people would get rich, but that's acceptable because it could be sorted out later when the productive forces were sufficient to support a true communist distribution of wealth. This is very similar to the views Marx expressed in Gotha, but more accepting of private property -- as long as it remains useful.

Maybe Deng was disingenuous and tried to sneak capitalism in through the back door, or maybe he really did believe what he said. But you can't dismiss his views as being non-Marxist ipso facto, because they are clearly derived from Marx's theory of history and expressed via Marxist concepts.