The capped length is identical at 147mm. The barrel diameter is 13.9mm vs 14.8mm for the MB. The section diameter where your fingers naturally fall is 12 mm vs 13 for the MB. The cap diameter is 17mm (not counting the craters) vs 16.7mm for the MB.
The nib is a #6 JoWo from Franklin-Christoph.
Thanks for asking.