I have an entirely different take on the question. What I believe the
differences are about can best be understood by comparison with the battles
inside the Second International with Rosa Luxemburg on one side and Eduard
Bernstein on the other. In the late 1800s capitalism experienced a
prolonged expansionary phase which led many Marxists to believe that
something qualitatively had changed. "Evolutionary socialism" was premised
on the belief that the institutions of monopoly capitalism could be
gradually transformed into socialism by expanding the power of the working
class through peaceful, legal parliamentary and trade union activity.
Luxemburg argued that the rising standard of living and democratic openings
were largely connected to the rise of imperialism which allowed the class
struggle to be co-opted in countries like England and Germany. While the
Kaiser was instituting the first social security system in modern times, he
was at the same time turning the territory now called Namibia into a
concentration camp, which served as a model for Hitler's camps years later.