What is difference between a plane scale and a diagonal scale?

A plane scale is a straight measuring tool marked with units, typically used for measuring distances on maps or drawings in a single dimension. In contrast, a diagonal scale includes additional diagonal lines that provide greater precision, allowing for the measurement of fractional parts of a unit. This makes the diagonal scale more versatile for tasks requiring fine measurements, such as architectural or engineering drawings. Essentially, the key difference lies in the level of detail and precision each scale provides.