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Optically I suspect they will be very close at identical f-stops.
That couldn't be further from the truth, unless you are only speaking of "sharpness".
The Zeiss will have a different cast, different overall drawing style, different bokeh, different flare resistance, different macro-contrast and micro-contrast, different distortion, different CA, different ...
The only thing similar will be the FOV.
And I am pretty sure the Zeiss has no focus shift issue as the L does (which is not an AF issue, for those who think it is).