What distinction causes confusion regarding Da Vinci's inventions?

Documented design versus successfully constructed device

The primary source of confusion surrounding Leonardo da Vinci's contributions stems directly from the fundamental difference between having a detailed blueprint or design documented in his notebooks and successfully constructing that design into a functional, built device during his lifetime. Many of his most celebrated concepts, such as the aerial screw and the armored fighting vehicle, existed only as schematics written in his unique mirror script within his codices. While he was employed as an engineer, his commissions often leaned toward practical needs like military engineering or stage machinery, meaning his purely speculative inventions, which far outpaced the technology of his era, often remained theoretical exercises rather than realized, operational machines. This dichotomy forces historians to define whether a sophisticated theoretical concept counts as an invention if it never left the paper.