Why do crisp bread rolls have more water than soft bread rolls?
There's several things going on here:


Water itself doesn't really make it crisp or not...per se.  What may happen there is that the water will release in the oven as steam and that contributes to a 'crisp crust'.  More water will thus generally mean a crispier crust - because it steams more.  You can accentuate this by baking in a closed container like a dutch oven or by creating steam in the oven artificially (thats what 'real' bakery ovens do, inject steam).
The reason bread is soft on the inside however has a lot more to do with two major things.


The sugar content
The fat content


Increasing both of these will make your bread softer.  So if your softer recipe also includes more these, thats why they're softer - not the water content.
The flour type...kind of.  Softness and chewiness aren't quite opposites, but if you're looking for Wonderbread, you'll want to avoid high protein flours and go for something like all purpose flour. 'Chewiness' can be perceived as less soft.  Chewiness is generally a result of more gluten.  With all purpose flour, you'll end up with less gluten and as a result, less chewiness.  Using a high protein dough, you end up with something chewy like pizza dough or such.  Since gluten forms easier with wetter doughs (thats what the whole no knead movement is about) - the water content also plays a factor here.  It will make it chewier - which can be interrupted as less soft.