I´m going to post this here because they closed the thread in where I was writing it...
This was the thread:
https://www.gtplanet.net/forum/threads/gt6-vs-forza-5-lighting.291328/#post-9018650
And my comment:
The difference in the lighting and graphics is quite noticeable.
I still think that the colour palette and lighting in Gran Turismo 5/6 is the most realistic of every game. GT tries to look as photo-realistic as possible giving a natural look to the overall game.
It looks "bad" at some points because you can´t rise the level of detail and the post processing (Antialiasing, texture quality of the environment, etc)
Forza 5 looks better because of DX11 features (materials can look as they really are and in GT5/6 you can´t have that), post processing effects are there but then they overdo the rest to look shiny/good/beautiful instead of like the real deal.
Cars in Forza 5 looks photo-realistic thanks to that (at least in autovista mode compared to the actual races, a friend has the game and made tons of pictures) and the laser scanned tracks are superb (Spa looks exactly like it is in real life) though then they add all the "NFS stylish" crap to it and it stops looking like it should.
They overdo things to gain the eyes of the people...but in Gran Turismo they try to do everything as it actually looks in real life. And the thing is that PD is trying in a 7 year old hardware which to me is way more impressive than what Forza 5 is doing...not having day/night/weather cycles...downgrading the game since E3...that says all.
PD has the better graphics engine no doubt of it (it does more stuff with less)...and the PS4 is a little bit more powerful than the "XBONE", just take a look at how realistic and natural Drive Club looks...compare it not with Forza 5...with GT5/6, and then you´ll have an idea of what we all can expect to see in Gran Turismo 7.
Sometimes is not the hardware though...is how you do it.