While most of my time spent in wine forums is on Rogov's side of the fence, I feel this particular question will benefit from the broader perspective offered by this side. So here it is:
The technical differences between Cava and Prosecco not withstanding, are there well defined stylistic differences between them and what are they?
From my limited experience it seems that Prosecco is intentionally made in a style, even when it is a brut, that is softer, rounder and overall elegant, working better as an apertif on its own or accompanying appetizers and light dishes, whereas Cava is produced as an angular wine, best described as agressive and muscular, whose tartness makes it a very good match with almost all foods, accompanying light appetizers as well as creamy pastas, seafood and meat. In my case, the fruit profile was considerably different, too, the Cava exhibiting the tartness of green apples and the citrusy acidity of lemons, the Prosecco showing a bouquet of white fruits: peaches and nectarines.
Did I observe accurately, or is it perhaps just a refelction of the limited sample I enjoyed?