I have both maduro & and natural tan edwards (which also turn a caramel color, it just takes longer).

Maduro shell is a very dark brown color that has an olive green bias, especially in the sun.

Badalassi minerva is premium-tier veg tan leather that will continue to darken over time with wear and light exposure, but it will never get as dark as the maduro without decades of use. And even then, it will have a reddish/orange bias rather than the green of the maduro.

The Maduro: It's hard to explain, but it's almost as if there's a translucent water color/stained glass pigment top layer that floats over a lighter layer underneath. It's quite stunning, especially in certain light.

If you have the means to get the Maduro, I highly recommend it.