They definitely have different case architectures..
Look at ZF vs GF vs Gen. ZF pretty much replicates the architecture spot on versus GF.
If you look at the case shape, the ZF side bevels are a touch thicker than GF, closer to gen. Morever, take a look at crown position, GF is a bit high where ZF and Gen sit lower. Even the shape of the crown. ZF and Gen at the bottom of the crown shape out to be \ /, versus GF has like a bevel into another circle..
I'm pretty certain the movement is different, as if they were the same movement, I think crown heights would be the same. The slightly different thickness may or may not make a difference. In titanium and ceramic watches, I suppose you'd feel the difference less because of the weight. My blue ceramic ZF Bathyscaphe weights about 105grams, I would think the steel variant is significantly heavier.
GF does achieve the look nicely however. The gen titanium version to my understanding is discontinued. Also, the GF titanium looks to have steel polished hands, where as gen titanium pics appear to have blackened steel polished hands. And if we're nit picking, the hour hand may be a touch thicker. Lol
I think the Bathyscaphe is by far one of the most wearable, versatile divers. Couple that with the perceived better QC of GF and a better movement, we may have a winner.
My blue Bathyscaphe has some QC issues that would be easily missed in QC photos, to the point where I told my td about them and it was very hard to capture with my camera.
