It is true that the most a socialist society has existed is only for a few years, a decade at most, because like all early capitalist revolutions, counterrevolutions have destroyed them. However, you can compare it to the theoretical component of Marxism. Despite the common ignorant and desperate attempt to defend bourgeois society with the words, "communism works
in theory", it is precisely because communism is dialectical that makes that its strength. Most bourgeois theories of government are metaphysical, i.e. abstractly. In order to simplift things, in bourgeois science you generally break things down into simple components.
Take for example the idea that democracy and dictatorship are two differenr kinds of
government, but socialism and capitalism are two different kind of
economies. We sometimes think because of this that we can have democratic capitalist societies, dictatorial capitalist societies, democratic socialist societies, and dictatorial socialist societies, depending on whatever is the
choice of government. In reality, government and economics are intertwined. Metaphysics, which is our typical laws of logic (identity, non-contradiction, excluded middle), is false logic, and reduces everything to a theory where everything works ideally. Dialectics, on the other hand, takes into account each and every possible factor. That is why Marx's predictions have been 99% true (I say 99% only because I don't want to make a universal statement). Using dialectics Marx predicted the existance of stagflation a century before it first appeared (which was one of many crises of capitalism). Earlier metaphysical studies of capitalism, e.g. Wealth of Nations, did not perdict any crises at all. What is eventually found dialectically is humans obey certain laws. Man's theories do not affect human development, human development affects man's theories. Hence we have no real choice of government. We always start with capitalist democracy (after feudalism). We always go to capitalist dictatorship when the bourgeois is threatened with socialism (which always happens). Man then always proceeds to socialist democracy, unless it is a backwards country, in which case, depending on other factors, it may become a socialist dictatorship. If the later happes, it will always return to a capitalist dictatorship, then to capitalist democracy, and then to socialist democracy. Marxism predicted all of the above, and so far, using Russia as an example, it has gone through capitalism, socialist dictatorshop, and all the way back to capitalist democracy. It was a perfect prediction. Damn I rambled on forever there didn't I?
So to compare things theoretically, which is identical to Marxism in practice, socialism is different in that all people participate in democracy instead of a few, and all workers are paid about what they work for instead of less than that. Economically, that is vastly superior, and allows for scientific management of the economy, which under capitalism cannot be done without ruining the market system on which capitalism is based. Thus the people have more ability to produce than in capitalism.