A TB20 comprehensively outclasses a TB10 in performance, range, and consequent mission capability.
The practical range, taking into account realistic reserves etc, is about double, for example.
The only thing they have in common is the airframe and the general layout, which is very nice. It's a great "passenger friendly" plane, matched only by the SR22 or the DA42, among the mainstream types.
I bought a brand new TB20GT (one of the last ones made) in 2002 and it was a great decision. It's great for decent long trips like
this.