no its not!
other than the in-your-face difference in rendering resolution, framerate is halved, so a lot of detail can be added.
but dont take my word for it, here;s digital foundry:
"Since the Gran Turismo series moved onto PlayStation 3, Polyphony has opted for 30fps replays, halving frame-rate in order to layer on additional effects and deploy higher detail models. This remains the case for Pro users running the 4K mode, and for base PS4 hardware operating at 1080p" (
http://www.eurogamer.net/articles/digitalfoundry-2017-gran-turismo-sport-ps4-pro-analysis )
of course they ommit referring to the letterbox resolution of replays, that is very far off from 1920x1080, but still..
anyway, replays look fantastic, but they are NOT gameplay.
and on that same article, in less than two lines is my fear:
"In like-for-like tests, we found that the PS4 Pro version held a virtually solid 60fps lock,
whereas base hardware can drop to the mid-40s in the most densely packed race scenes. This is a welcome enhancement - dropped frames means a disconnect in terms of ..."
not looking to buy a ps4 pro. iffy framerate on my base ps4 will be such a huge turn-off.... this is my one and only request...