I own several Canali jackets and suits, and several Zegnas. As Robasaurus has pointed out, not every cut is the same... but I can say that my Canalis tend to fit me a bit larger than my mainline Zegna stuff. My Zegnas feature trimmer fits and higher armholes. I'm not sure if there's more waist suppression in technical terms based on the drop, but the shoulders seem to start trimmer and the whole jacket follows suit. (Ha, two "suit" puns in one thread.) As others have noted, the shoulders are built up more for a more square looking overall shape, while the Zegnas have softer and more sloping shoulders.
I think if you want a more Zegna-like fit, you should consider sizing down. You said you are sure you have the "right" size, but remember, the "right" size is going to vary depending on cut, manufacturer, etc. You don't have one holy grail size that is always appropriate.
Your other option may be to have the waist taken in, but you'll have to live in general with the shape of the shoulder.