your question is not very specific. Of course in every program the implementation might differ a bit, but in general the programs should give the same accuracy using the same approximations
I assume you ask this question because you observe some unexpected deviations between old Gaussian results and your current Turbomole results. If you give us more information we can say a few words on it.
Which calculations your are doing?
If you are doing DFT calculations for example there can be several sources for differences between different programs. The integration grids might be different and this effect is not that small if you compare total energies, but should be insignificant if you look at energy differences. A more "famous" problem when comparing to Gaussian is the B3-LYP functional. Gaussian uses not the "official" variant, but a modified one. But how can use the Gaussian version in Turbomole as well.