Difference in Art Critics Rosenberg and Greenberg?

Difference in Art Critics Rosenberg and Greenberg?
I am doing reading of there Abstract Expressionism criticisms and I am failing to find the main things they disagreed on. So my question is what were there main differences?

I know that Rosenberg was influenced by Sartre and his ideal were Kooning’s work. Also that Greenberg preferred Pollock and color field painters.

I’m just failing to see their difference in perspective.
Someone that knows about them please help or link me to an article that compares them, which ever is easier for you.
Thank You

Harold Rosenberg (1906-78), interpreted painting almost exclusively in terms of existential drama, the artist as a hero using painting to express individuality and self.
Clement Greenberg (1909-94), saw formal invention as the fundamental element, paintings were flat arrangements of colour and shape and should have no illusion of depth.………

“The impact of Rosenberg and Greenberg in their heyday was as compelling as that of tribal shamans.

The term “avant-garde” meant something crucial to them. It preserved one essential concept of the Leninism that had intoxicated their generation of intellectuals in the thirties: the vanguard, whose alienated, conspiratorial, happy-few solidarity is an earnest of revolutionary rectitude. Greenberg carried over, as well, the belief in history as a predetermined unfolding, which he transposed from economics to aesthetics. In effect, he assigned the role of the bound-for-glory proletariat to the fundamental characteristics of artistic mediums—thus his incessant celebration of “flatness” in painting, banishing the opiates of representational illusion. Rosenberg’s polemic was rangier. His Action-painting doctrine—if so nebulous a formulation, advanced in a famous essay in 1952, can be called that—enlisted Sartre’s existentialism in the cause of exemplary artist-heroes for whom painting had become “an arena in which to act. . . . What was to go on the canvas was not a picture but an event.” He could sure sling the lingo, writing that the Action painter “begins with nothingness. That is the only thing he copies. The rest he invents.” (Rosenberg was esteemed by Parisian intellectuals, including de Beauvoir and Merleau-Ponty; Greenberg, contemptuous of recent French art, wasn’t.) Rosenberg disdained to clarify how to square an exciting “event” with the residual fact of something—a relic? detritus?—that is hung on the wall to be enjoyed. You got it or you didn’t. But then visual acuity was not his forte. It was Greenberg’s, to a fault. When Greenberg looked, everything in the universe except optical fact fell away.”