I suspect you have been filling in the canvas valleys between the ridges when you were rolling, so that you get a mechanically flat surface.
You can do that too with spraying, with very aggressive coats. But since you are applying thinner coats with spraying, the canvas is able to soak up the paint equally in both ridges and valleys, and that ripply contour is maintained rather than being filled in.
You could apply a lot more thinner coats to get the "filled in" look with spraying. It sounds like your rolling technique is to inundate the print in a single coat.
You can also inundate the print with spraying, which I used to do with very water proof Sunset Select and Glamour II. I would apply two thick coats with no time in between, with the paint so thick it was on the borderline of running. Was definitely a different, more "filled-in" look than I get with the gentler, multi coat spraying I do now as required by gloss canvas.
But bottom line is, thin coats will have better transparency than thick ones. But the flip side of the coin is, you get very different reflective qualities with "filled in" canvases versus canvases where the ridge/valley contours are still present.
Let's suppose there's a light source coming from right behind our heads.
--With a "filled-in" coating the reflections will be something like you see on glass. You'll see small, almost specular reflections confined to small areas.
--With a "ridge-valley" canvas, the reflections will be more diffuse and less intense, but they will slightly haze out a larger area. Which I guess looks like "sheen."
It all comes down to aesthetics.
Of course there are other things that affect a sprayed surface coating. If you spray from too great a distance, or with too little spray for the ambient temperature and humidity, the paint will land on the canvas is a kind of tacky condition. That leads to a hazy looking, sort of matte surface coat. It's important that paint land on the surface very wet, even if it then dries quickly.
I now use very thin coats because my gloss canvas is not very water proof. I do a few things to assure super-even coats and consistency. On panels where I tape up my canvases for painting there are tick marks top and bottom at 4" spacing to help me get very evenly spaced swipes. I also time each swipe with a little metronome clipped to my shirt. And I always weight the gun after each coat to double check the amount of paint applied. It's worth the effort.
