Odyssey changed the GFX a lot.
Check the shots of my carrier from XB and from PC.
I'd say the differences are quite big.
Edit: and the differences in planetary surface rendering are even bigger.
there are three simple things in effect here that greatly improve the look of assets without actually requiring much of any difference in processing.
1. The light source is whiter.
2. Moving to a material/physical based renderer and allowing the materials selected for parts of textures to be consistently mapped often results in a better image than previous/traditional setups where artists bake specular and reflective maps into the textures in a more "this looks good to me" kind of way per texture.
3. Your xbox has different quality settings than your pc
Likewise, there are changes to the shaders on the surface ...for sure. but they're not doing anything significantly different from horizon shaders, they're just doing it on a better physically based rendering texture methodology. This doesn't require more processing power at the time of rendering. The difference with physically/material based rendering happens at the mapping side ...in creating the texture assets. Before the artist or programmer decides to use them.
I would expect to see more shader effects or better anti-aliasing and more realistic noise etc in a new rendering to constitute more resources - not just nicer looking textures. Nicer looking textures doesn't change rendering requirements unless they're higher resolution. Instead, we see less shader effects in odyssey, the same old anti-aliasing issues, and the addition of default features to reduce the rendering resolution (and still being slower than horizons). All things that point to doing less but requiring more ...not doing more and requiring more.
And regardless of how much you believe that, it's irrefutable that even if you remove all of these variables of ship models, planetary surfaces etc, you still measure a massive performance gap between horizons and odyssey and this means this is a performance gap that is constant. It may vary a bit player to player but on most over-capable systems for the resolution in-use it would be measured at roughly 50% it seems. That means if this was eliminated - regardless of how much harder things are working on surfaces and stations, you would see a pretty significant improvement in performance. One that would likely bring such performance back in line with horizons and so be entirely capable of being released on consoles, etc.
We know the engine was heavily modified to elite dangerous when it was released, we know this happened again in horizons release. I think the re-sync to cobra for odyssey did not come with the same level of engine developer and elite dangerous developer experience to implement that customization again. It was rigged up to at least work, but it's not working as well as it did in horizons. Not that it's doing so much more that it can't do the job any faster.