The terms "katana" and "uchigatana" are often used interchangeably or with slight variations in meaning depending on the context and historical period. However, there are some distinctions that can be made between the two:

Historical Usage: The term "uchigatana" is primarily associated with the early forms of Japanese swords from the Heian period (794-1185). During this time, the uchigatana referred to a style of sword that was worn with the cutting edge facing up. It was primarily used by foot soldiers. On the other hand, the term "katana" emerged later during the Muromachi period (1336-1573) and referred to a longer sword worn with the cutting edge facing down. The katana became the primary weapon of the samurai class.

Blade Curvature: Uchigatana blades tend to have a less pronounced curve compared to katana blades. While both swords are curved, the uchigatana typically has a gentler curve, while the katana has a more pronounced and iconic curve.

Length and Size: Katana blades are generally longer than uchigatana blades. Katana blades typically range from 60-75 centimeters (24-30 inches), while uchigatana blades are often shorter, around 50-65 centimeters (20-26 inches). The handle lengths can also vary between the two swords.

Wearing and Use: Historically, the uchigatana was worn with the cutting edge facing up and was primarily used by infantry soldiers. The katana, with its longer length and more curved blade, was worn with the cutting edge facing down and was favored by samurai warriors on horseback. The katana became renowned as the iconic samurai sword.

It's important to note that terminology and definitions can vary between different historical periods and regions, and there can be overlap or variations in usage. The exact definitions and distinctions of uchigatana and katana can depend on specific historical contexts, regions, or sources.