As I watch my tablet upgrade to Android 9, I find my mind flashing to when my phone updated closer to Pie's release--and the distinct feeling that "All my icons are different for no good reason. Other than that: it's hard to tell anything changed."
But it's worth noting, I use my Galaxy Tab S3 excessively every day, but my Moto X4 is only lightly used. Because unless I'm literally walking around in public or answering a text message in the middle of the night: there's a 95% chance that I'll use my tablet instead.
Both devices were released in 2017 and had Android 7/Nougat as their original operating system image. The primarily difference is my Android One edition got Pie around Christmas time and my Sammy gets pie to the face shortly after Android 10 launches.
That's par for course for Samsung's tablets in the past, except seeing three major OS versions on one tablet is odd for them; I had the upgrade to Android 8/Oreo to be the Tab S3's final operating system based on previous experiences with their high end tablets. I've owned a lot of those.
If anything actually changes that makes me give a flying floop, it'll probably rely on Samsung's UI customizations. Because on the more "Pure" load my phone uses, "Damn it, my icons are all different", really was the most noticeable difference. The bit about text selection might be more in my face on a tablet but wasn't necessary on my phone, nor is it on my big screen; especially with pen in hand.