The GTS-R was just the homologated version of the HR31, there were "GTR" before and after the GTS-R, however for that 2yr period it was the GTS-R.
There was a GTS, GTS-X and GTS-R in the HR31.
Obviously Nissan didn't design the R32 GTR/RB26 overnight however there are certainly similarities carried across, engines are bolt in/bolt out virtually as an example. So certainly some things were kept near the same. Diff was similar in terms of R200 short/long nose etc.
So certainly some was same, and there was certainly lots different.
A HR31 GTS-R is closer to a GTR than a DR30/KP is to a GTR for instance if that's what you mean?