Katana has longer hilt hence better leverage for power strike. Jap Metallurgy are better, folding steel technique to weed out impurity. The curve blade was design to cut better than straight blade, cutting in diagonally. The blade is shorter and stiffer, less flexing when stabbing. Katana clay tempered the edge so the it's harder and easier to cut, while the spine of the blade is flexible and easy to bend.
Nuff said.