I had the same question as you and skimmed Eichenwald's article. He claims that his own words were attributed to someone else (Blumenthal) in these manipulated leaks, and subsequently parroted by trump. He had written a long article about Benghazi, and the email leak takes Blumenthal's quotation of that out of context, misattributing it.
It checks out, and at least on that point Eichenwald seems to be closer to the truth than Greenwald is (Greenwald hardly has anything to say in his own article about the details of the Eichenwald situation, only name-drops and sneers). It looks like this is Greenwald raising his hackles because he perceives his work with wikileaks to be under attack from Eichenwaldl.
It's not "significantly rewritten". Some details were added and clarified. Most relevant is the fact that the most recent version, and all other versions (I read them all) make it completely clear that Eichenwald has no reason to think, and does not say, that the emails as leaked by Wikileaks are fake. So Greenwald is still lying, no matter which version you are looking at.
It checks out, and at least on that point Eichenwald seems to be closer to the truth than Greenwald is (Greenwald hardly has anything to say in his own article about the details of the Eichenwald situation, only name-drops and sneers). It looks like this is Greenwald raising his hackles because he perceives his work with wikileaks to be under attack from Eichenwaldl.