It seems pure marketing to me,
I have Surface book 2, Surface pro 6,
At the same time I bought Surface Laptop for my girlfriend.
So x3 MS products in one household.
1. Surface book 2 - I didn't found anything better in 2018, so I don't regret spent €3000. But, no one can see in the future, but as for now, it seems to be my last MS premium product. I still have Win 1803 from 2018, because guys at MS are not able to make proper drivers for their own products. Issues with firmware, issues with every new version of Windows, you don't have to believe me, just type in Google "Surface book 3 win 2004".
2. Surface pro, no problem so far, but unusable as a tablet. Window on a tablet is a joke.
3. Surface Laptop, obviously a little bit better then my SB 2, because of the absence of the Nvidia graphic (trouble child), but wors then Surface pro with similar updates issues as my SB 2.
Build quality is only good enough on my Surface Book,
If you just spit on Surface Laptop or Pro, you have immediately a dent,
and don't buy a black Surface Pro, the color is not anodized like on the HTC M7 back then.
I personally don't see myself buying any of MS products again in the observable future.