Private ownership of industry, which Italy and Spain and Germany all had, yet the Soviets did not.
Anyway do you contend that the Soviet Union, which referred to WWII as "the great patriotic war" was not nationalistic? I say they were, every bit as much as Spain and Italy and for the same reason: they dictators in charge needed to create a mythology around their nations in order to justify that their state was legitimate and strong so they could hold onto power. Indeed, the first thing that happened when the soviets collapsed was the splintering of the Soviet Union into its component parts.
As I've said though, the thing that set the Soviet Union apart from the fascist states of Italy, Spain, and Germany was the private ownership of industry.