It is double edged, has extensive moves for thrusting, can be utilized more effectively in grappling and can be used in half swording (gripping the blade with two hands and using the handle and quillons to bash the enemy like a mace). Making it overall better vs. armour but also good vs. unarmoured. You can't do Zwerchaus or murder strokes with the katana.

Longsword techniques such as that of Fiorei dei Liberi, are more versatile, mixing grappling, disarms and technique rather than the speed driven techniques due to the cutting centric nature of katana use. Lack of quillons to trap the other opponent's weapon and emphasis on quick single to double cuts, because clashing swords (continuously) with your opponent was discouraged by Japanese sword masters.

It also had slightly better steel, where the steel would flex when hit in order to distribute the energy along the blade. Contrast that with a traditionally made katana where the edge is harder than the back, which makes it rigid but also brittle.