Whats the difference ? 4150 question !

LOL...this is one reason I say not to select a carb based on CFM. It’s just not really representative of what you may or may not be getting.

Venturi diameter first, throttle blade diameter after that and the CFM is what it is. The more “modern” carbs with the better shaped main body will flow more air with a smaller venturi, and its cleaner, smoother air.
In a full race car what would be the issues of using a 1.56 venturi & 1.687 throttle bore, downleg booster 830 hp on my 471 stroker?? it's a smooth inlet main body with removable air bleeds.
Would the velocity be slow?