The terms "Iaido katana" and "katana" both refer to Japanese swords, but there is a slight difference in their usage and context:

1. Katana: Katana is a general term used to describe the traditional Japanese sword with a curved, single-edged blade, circular or squared guard (tsuba), and long grip (tsuka). The katana is a versatile weapon historically associated with the samurai class and is known for its sharpness, cutting ability, and use in close combat. It has a wide range of applications, including warfare, self-defense, and ceremonial purposes.
2. Iaido Katana: The term "Iaido katana" specifically refers to a katana used in the martial art of Iaido. Iaido is a discipline focused on the art of drawing and using the sword in a controlled, precise, and mindful manner. The Iaido katana is typically an unsharpened practice sword known as an Iaito. It closely resembles a traditional katana in terms of shape, size, and design but is specifically made for training and practice. The Iaito replicates the weight and balance of a real sword while minimizing the risk of injury during training.

So, the main difference between an Iaido katana and a katana is that the former is specifically used for training and practice in the martial art of Iaido, while the latter is a general term encompassing the traditional Japanese sword used in various contexts.