The difference between a katana and a ninjato is a subject of debate and misconception due to the lack of historical evidence regarding the ninjato. However, in popular culture, the term "ninjato" is often used to refer to a straight-bladed sword associated with ninja warriors. Here are some general differences based on their portrayals in popular media:

1. Blade Design: The katana has a curved, single-edged blade that aids in cutting and drawing techniques. It typically features a gentle curve and a long grip for two-handed use. In contrast, the ninjato is often depicted as a straight-bladed sword with a shorter length. Its blade resembles a tantō or a wakizashi rather than a typical katana.
2. Usage and Purpose: The katana was historically used by samurai warriors and was their primary weapon. It was designed for versatile combat scenarios and was known for its cutting and slashing capabilities. The ninjato, as portrayed in popular culture, is associated with ninja warriors and is often depicted as a weapon used for stealth, agility, and quick strikes. It is commonly associated with the clandestine operations and tactics of ninja characters.
3. Historical Basis: It is important to note that the ninjato does not have a firm historical basis. The depiction of a specific sword called the "ninjato" originated in modern times and is largely influenced by fictional representations in movies, novels, and games. There is limited historical evidence to support the existence of a distinct sword design used exclusively by ninja warriors.
4. Historical Accuracy: While the katana is based on historical records and represents a widely recognized sword type, the concept of the ninjato is not rooted in historical accuracy. The portrayal of a straight-bladed sword associated with ninja warriors is largely a product of imagination and artistic interpretation in popular media.

In summary, the katana is a historically recognized sword with a curved blade primarily used by samurai warriors, while the ninjato is a term primarily used in fictional portrayals to describe a straight-bladed sword associated with ninja characters. It is important to distinguish between the historical reality of the katana and the fictional representations of the ninjato in popular culture.