Nah, Greens and The Left are basically the same ideologically. All the differences are cultural.
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Well, that is contrary to the opinion of basically anyone knowledgeable about German politics.
I think this is a case where they can't see the forest for the trees. They are focused so much on detail they can't see the bigger picture that they are indeed basically the same. Maybe not the same, let me put it this way, the differences between the Greens and the Left are less than the differences between the left and right wings within other single political parties.
I fail to see how someone which annual birthday wishes to Fidel Castro and is nostalgic for DDR (a few old school PDS members) and someone like the minister-president of Bade-Wurtenberg (a green sounding like an old style christian-democrat) are similar.