I haven’t seen an up to date list (an old thread is around here in the forum somewhere), but it will be out of date even more once Nuendo 10 is released.
But basically Nuendo 8.3 = Cubase 9.5 plus extra post production and game audio features.
The comparison is more clouded since the release of Cubase 10, since Cubase 10 added several features that were once exclusive to Nuendo 8.3, plus Cubase 10 leapfrogged over Nuendo 8.3 in some very key areas like interface, variaudio 3, etc… so unless someone has been maintaining the comparison list, it will be very out of date by now.
However, when Nuendo 10 is released soon, the comparison will look like this: Nuendo 10 = Cubase 10 + extra post production and game audio features. Hopefully at that time, Steinberg will release a very clear updated comparison page to make it easy for people to understand.
And going forward, Steinberg has indicated that the gap between Cubase and Nuendo release cycles will be greatly reduced, so we won’t have as much of an issue. Previously, it took many months for Nuendo to get some of the newest Cubase features, contributing to a “lag” or “leapfrog” effect, but that is going to be changing.
Hope that helps a little – perhaps someone can find that old comparison thread for more info if you want to dig into the details, and then you can extrapolate with the latest news. Bottom line though, is that if you want the more advanced surround support and more advanced post production and game audio tools, then you’ll want to move over to Nuendo.