There is more to it in racing games than outright visuals. The more powerful hardware allows for much more complex physics simulations so you can get a much more accurate experience. It's why games like iracing whilst ugly cant be done on current consoles due to the physics simulations. As someone who has played sport for probably close to 1000hours I can tell you right now though the environmental detail in the GT7 trailer is leaps ahead of sport. There is also the rearview camera and mirrors, in sport after about 100m or so the world literally disappears and has a really low resolution, in 7 that appears to be completely gone.
Gran Turismo can never approach the likes of PC racing simulators because it needs to be playable and competitive on a controller.
The ugliest part of the GT7 trailer isn't the fact that it's the GT:S engine with some extra features, but how lifeless the car is, and how the wheel is so disconnected from what the car is doing.
You can turn all assists off in GT:S and the game is still driving the car for you. When you steer using an analog stick you aren't rotating the front wheels, you're requesting how hard you'd like the car to turn, and the front wheels are making all kinds of superhuman micro-corrections hunting for grip.
The cockpit whee reflects precisely how much your stick is rocked over, but the angle of the front wheels is entirely independent.
When driving with a racing wheel it's then 1:1, but it's a lot more effort and skill required to carry the same mid-corner speed that you can using a controller with all the assists turned off.
When GT:S first launched the Driving School Gold medals were extremely challenging to get, and the cars had much more realistic levels of grip, not far away at all from the well-regarded PC racing simulators.
The first big patch increased the tyre grip all round massively and made the cars much easier to drive and it was warmly received and praised. The Gold medal times were also relaxed by whole seconds in some cases. For me the game became worse and I shifted focus back to PC sim-racing where it's buy a wheel or go home.
The default ABS in GT:S isn't even ABS, but computer perfect context aware trail-braking baked in. Braking is entirely down to timing and no down to any feel or weight shifting skill. ABS on 'Low' is actually closer to real ABS.
Gran Turismo can never be a realistic simulation. The controllers can't allow it and the bulk of the casuals that buy it do not want that. GT:S launched as close to a PC racing sim as possible and quickly walked back on it.
That said: GT:S is the best racing game on console because it is the only one where you can race online with any expectation of good racing (once you get to and beyond DR:A SR:S). All other games pretty much need you to organise or join private leagues to have that. And AI will never be as challenging as good humans are in race craft.
This GT7 trailer disappointed me with how utterly lifeless and cartoonish the car was moving around—supernaturally stable under braking—and how clearly disconnected the steering wheel is from what the front wheels are doing, with it again being just a visual representation of how far you've tilted your stick over.
Do not expect better "physics" as far as driving goes, regardless of the beefier CPU. It never held that area of the game back as something like LiveForSpeed can demonstrate when running on a toaster.