I am going to answer this for myself. I ordered the tire, mounted it on a 31mm rim, took some pictures and measurements, and took it off.
Basically, because of the tread pattern, it has a more narrow contact area that the Innova 2.1.
The 2.35 measurement is the farthest outside sidewall width that I could get when I had 60lbs in it. The sidewall bulge is much wider than the tread, unlike the Innova where the tread is wider than the width of the sidewalls.
Note the tread and layout pattern and how the 2.1 Innova yields a wide contact area than the 2.35: