hi… are there to different tools?
As far as I know, you can only sculpt on a multires enabled mesh, not on a subsurf modified one.
You also can’t do some operations on a multires mesh, like extrude and bevel, unless you apply the multires to the mesh, or use a modifier in the case of the bevel.
nitpick*
Sculpt can work on any mesh, but only on vertices… You can sculpt on a subsurf mesh but only the control vertices are affected not the “interpolated” ones…*nitpick This is actually quite nice for tweaking a mesh (I use a tablet and find the sculpt “grab” tool easier to use than “soft selection” as a stylus has no mousewheel…
The lack of editing multires is a pain, Hopefully the new multires modifier (google summer of code) will get completed and merged to trunk…
Still, you can’t do those sorts of edits on a mesh with “Shape keys” either… a bit of a pain!