My only experience between the two may not be definitive but I’ll just give my own experience.
Occasionally when someone links to a previously asked Q it takes me to the non mobile version of the site.
It takes much longer to load, sometimes crashes, and trying to type an answer is agonizingly slow and clunky.
The mobile version has eliminated flagging from it’s interface as well as the info panel on the side with who won what award or reached 10K and such not.
So the mobile is a slimmed down version of the regular.
I think its just as well they took the App out as it was so crippled in essential functions as to be useless for anything other than reading only. You couldn’t really participate through the App.