The term "Iaido katana" is not commonly used to refer to a specific type of sword. Rather, "Iaido" refers to the martial art itself, which focuses on the drawing, cutting, and resheathing of the sword in a controlled and precise manner.

In the context of iaido practice, the term "iaito" is often used to refer to a training sword designed specifically for iaido. It is an unsharpened replica of a katana, intended to replicate the weight, balance, and overall feel of a real sword while ensuring safety during practice. The iaito allows practitioners to perform the techniques of iaido without the risk of accidental injury.

On the other hand, a "katana" typically refers to a sharp, functional sword with a long curved blade, historically used by samurai in combat. It is a lethal weapon with a sharp cutting edge and is not specifically designed for training purposes.

So, in summary, the key difference lies in the purpose and design of the sword. An iaito is a training sword designed for iaido practice, while a katana is a functional sword historically used in combat.