The biggest takeaway is the amount and also quality of detail you see way into the horizon or the amount of detail that exists way above the immediate driving atmosphere in the clouds etc... This is certainly not a linear game skimping on details in the traditional sense. Before you approach bridges in DC, you see them from far away on approach, they're all massively detailed, the water bodies below them or elsewhere move and look real and don't appear like flat textures on approach. Couple that with cars on these tracks locations that never skimp on detail, high poly high detail cars, perhaps some of the most impressive cockpits we've seen in a racer with a detailed enough driver, wipers that animate superbly. Then we have the excellent lighting that impacts all these high end assets and details, when the sun hits the glass approaching a corner in India, it's almost blinding. Hell, you see dry streaks on your windshield in dry weather when the sun hits the glass. Cars stay wet and actually look wet when they go through torrential periods, brake calipers hot up and are visible during certain race cams.
As a linear racer they could have skimped on a lot of details, they didn't, they could have skimped on draw distance, they didn't, they could have made water bodies that are much further away from the player look flat on approach like FH3 does just a few feet away but they didn't, they could have made mountains 2D bitmaps, flat or untextured but they didn't. They could have baked their lighting to save performance or suit a linear track profile, they didn't. They could have skimped on their cloud render and skyboxes with a cheaper alternative, they didn't. That's the point really, so many areas that people would not immediately notice they could have skimped detail, but chose not to.
The point is, in any scene in DC, with it's huge draw distance, a high level of detail in the environs/track/location, better looking and more detailed cars, better lighting, better effects (debris, weather-rain, lightning, precipitation changes, dry weather-dust pickup etc.) POM, quality of foliage..DC is always doing much more than FH3 per scene. So if one says they prefer how FH3 looks, that's fine, they may prefer the sunnier locales but technically it's not even close and visually there's no doubt which racer looks more authentic and more visually stunning. That's why when you do a video comparison with all racers, it's not even a contest, some racers look comical in contrast and this is where all the high detail, great lighting and volumetrics of DC comes together.
One thing is sure, I've zoomed in on many details in DC and it's amazing how much they didn't skimp on. I've zoomed in on trees, water sources, rocks, cars, mountains, they're all pretty kosher. I'm sure there are some shitty compressed Jpegs of DC out there showing stuff no one else have noticed during extended play, but all the pics I've shown of FH3, even the video of the hummer were pretty good quality. The pics were PNG at least. There's no need to be disingenuous about it.