Not much of a comparison really. Perhaps a better comparison would be Bagration to the whole Normandy campaign. Both seriously eroded the German army's resources. In that respect more significantly in the East.

These figures may underline my point...

German Casualties on Eastern and Western Fronts.

Eastern Front

Month - KIA - WIA - MIA - %MIA

June - 10,629 - 41,165 - 73,723 - 58.7%
July - 30,420 - 131,732 - 238,284 - 59.5%
August - 30,636 - 152,484 - 191,557 - 51.1

Western Front

June - 4,975 - 14,631 - 15,848 - 44.7%
July - 10,839 - 38,824 - 55,135 - 52.6%
August - 7,205 - 13,605 - 127,633 - 86.0%

But then Cobra was merely the breakout phase of the Normandy campaign and was against a pretty worn down German army. As I said before it would be better to compare the Normandy Campaign to Bagration. Cobra was a small operation compared to Bagration.

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"Watch that Fu*ker, he'll 'ave someones eye out!" King Harold at Hastings 1066.