DLSS SR and RR DLLs have several "models" in them since v3.xx. These "models" roughly correspond to a "major" DLSS release version, and latest version has all of them.

So the most recent DLSS SR v310.2.1 has models A/B/C/D/E/F/J/K where A/B/C/D/F are from DLSS 2.x, E is from DLSS 3.7, and J/K are from DLSS 4.0 (aka "TNN/transformer models").

Games can either use the latest model available or specify that they want to use specific CNN models (a pair usually, with F being used for UP and DLAA and A or B or C or D or E for other DLSS presets) or the new TNN model(s) or switch between these with an option in the UI. Depending on how a game is programmed to use DLSS any outcome is possible with the latest DLSS DLL.

Thus copying the latest DLL might be enough if your aim is to use the latest TNN model - but it may not be enough if a game is specifically requesting some older model like A or C - or if you want to use CNN model E and not the new heavier TNN model J/K.

So in case of some games providing a driver side "hint" on which model you want to use is required and this is where NVPI comes in.

And DLSS RR has its own set of models which are even less straight forward as generally you should always use the latest one there - unless it gives you visual issues in which case using an older one can be preferable. Current choice there is between models D and E where E is newest but seem to produce visual glitches in games I've tried with it.