People tend to confuse the abilities of Toshiro’s Zanpakuto, Hyorinmaru, and Rukia's Sode no Shirayuki, but the fundamental difference is that Toshiro's blade is an external elemental creator, while Rukia's is an internal temperature manipulator. As the ultimate ice-type weapon, Hyorinmaru actively commands the atmosphere, generating and controlling vast amounts of water, moisture, and ice to crush opponents with massive frozen structures and dragons.
In contrast, Sode no Shirayuki does not actually produce ice out of thin air; instead, it brings Rukia’s own body temperature down to absolute zero, turning her entire physical form into the source of the freeze. The beautiful ice formations that appear around her are just the natural moisture in the surrounding air instantly flash-freezing the second it makes contact with her sub-zero body, shifting her ability away from Toshiro's wide-scale weather manipulation and into the realm of precise, lethal thermal control