1. Rated Current (Io): The ST part is rated for 20A per diode, whereas the ON part is rated for 10A per diode. This is not merely a matter of derating. The ON device's chip area or technology appears more optimized for cost, resulting in inferior thermal performance and overload capability compared to the ST part. Substituting the ON device in applications near or exceeding 10A will cause excessive junction temperature, accelerating failure. 2. Forward Voltage Drop (Vf): The ST part specifies 800mV @ 20A, while the ON part specifies 850mV @ 10A. The differing test conditions make a direct comparison misleading. However, at a common current level (e.g., 10A), the higher-rated ST device typically exhibits a significantly lower Vf. Using the ON part at the same operating current will result in higher conduction losses (P = Vf I), reducing system efficiency and increasing heat generation. 3. Reverse Leakage Current (Ir): At 100V, the ST part's Ir is 10µA, compared to 100µA for the ON part—a full order of magnitude difference. This indicates a difference in the Schottky barrier metal or fabrication process between the two devices. Higher leakage current increases static power dissipation under high-temperature, high-reverse-voltage conditions, adversely affecting system efficiency (particularly standby efficiency) and thermal management.