Differences in Forza Titles. Why so much between Motorsport and Horizon?

It’s quite clear you’re going for immersion here with how good these games look and how well the physics are programmed, but why so much difference between the 2? I mean really all you need to do to Horizon is add the Horizon features ( music festival, open world, etc etc ). I would much prefer to use Motorsport as my ‘track day’ game and Horizon for everything else. I just don’t understand why they have to look and sound so different from each other? Does it not make more sense to make them almost completely similar aside from the minor game mechanics differences? I find Motorsport much more forgiving in the driving physics dept so if your argument is to make it easier and more accessible, I’m afraid you’re missing the mark.

I just feel like the 2 could be much closer in similarity than they are. My biggest beef with Forza tbh.