Couldn't answer that one...
ZB not only does sculpting, but you can pose your models (I use it just to pose them... not for animations) and a plethora of other things beyond what I dreamed it was capable of.
It would not be fair to compare the two.
Most likely you are correct, (I haven't explored the capabilities of 3D brush...) but then, I never considered Hex to be more than a handy modeling tool with a workflow that I still think is sweet. I didn't think 3Dbrush ventured into that arena (box modeling, facet modeling, dynamic geometry, etc.), so I wouldn't compare it to Hexagon either. I think they are different tools each with their own values.