The terms "nodachi" and "odachi" are sometimes used interchangeably, and their precise definitions can vary depending on historical context and interpretations. However, there are generally understood differences between the two:

Nodachi:

• The term "nodachi" translates to "field sword" or "field great sword."
• In some interpretations, the nodachi refers to an extra-long sword with a blade length of approximately 90 centimeters (around 35 inches) or longer.
• Nodachi blades often feature a straight or slightly curved profile and were typically wielded with two hands due to their size and weight.
• Nodachis were primarily used by foot soldiers or ashigaru (common foot soldiers) in battle scenarios where the extended reach and cutting power of the weapon were advantageous.
• It's worth noting that the term "nodachi" can sometimes be used as a broader term to encompass any long Japanese sword, including both curved and straight blades.

Odachi:

• The term "odachi" translates to "great sword" or "large sword."
• In some interpretations, the odachi refers to an exceptionally long sword with a blade length that typically exceeds 100 centimeters (around 39 inches).
• Odachi blades often have a curved profile, similar to a katana or tachi but longer in length.
• Due to their immense size, odachis were less commonly used in practical combat scenarios and were often displayed as symbols of status, ceremonial weapons, or used for martial arts training.
• The handling and use of an odachi could be challenging due to its size and weight, requiring significant skill and strength.

While the distinctions between nodachi and odachi are not always clear-cut, the general consensus is that nodachi tends to refer to a straight or slightly curved extra-long sword, while odachi refers to a curved, exceptionally long sword.

It's important to note that historical terminology and interpretations can vary, and the precise definitions of these terms may differ depending on the source or school of thought.