I finally bothered to reinstall Horizons to do some experiments by taking the same screenshot in Odyssey and Horizons (as close as possible) and comparing the two directly. Obviously not gonna bother with stuff like planet surfaces since those vary wildly, but there's a lot of differences to be found in space as well.
First set of screenshots - take in the Wolf 1241 hazres:
Odyssey:
Horizons:
While I prefer the overall look of the warmer color scheme in the Horizons shot, The intense brightness found in the Odyssey screenshot is more realistic. This particular hazres is a mere 55ls from its parent star, so it should be as blinding as it is. The only downside is that the intense reflections on the asteroids really highlight the anti-aliasing issues found in Odyssey, but those should be rectified in an upcoming patch.
As I was writing this post, I decided I should head to another planet in the same system to see how the brightness scale changes with distance. This next set was taken from a planet a little more than 3kly from the star:
Odyssey:
Horizons:
I tried a couple different spots in the ring before choosing this one, and something I noticed is that the closer I got to the gas giant eclipsing the star, the more intense the brightness became, but I only noticed the effect in Odyssey. It's almost as if the gas giant was refracting the starlight differently. Sadly I didn't take any screenshots until I'd chosen this location, but I found it quite interesting. I may go back later and try to capture it.
Bonus Odyssey image - shot this half-eclipse in the same spot as the first comparison about an hour later. Really shows how much the lighting in this game can vary even in the same location: