1. Rated Current and Forward Voltage Drop: The ES2J has a rated current of 2A, whereas the US1J is rated for only 1A. At the same 2A load, the US1J would be severely overloaded, leading to thermal runaway and failure. Even at 1A, while both diodes share a nominal maximum forward voltage (Vf) of 1.7V, their actual Vf-temperature characteristics may differ due to variations in chip technology, impacting power dissipation and thermal design. 2. Reverse Recovery Characteristics: The ES2J features a significantly faster reverse recovery time (trr=35ns) compared to the US1J (trr=75ns). This indicates lower switching losses for the ES2J, making it suitable for higher-frequency switching circuits or applications with stringent efficiency requirements (e.g., PFC stages in SMPS, flyback snubbers). Employing the US1J would result in higher switching losses and noise, potentially degrading overall system efficiency and EMI performance. 3. Static Parameters and Leakage Current: At a 600V reverse bias, the US1J's reverse leakage current (10µA) is double that of the ES2J (5µA). In high-voltage off-states, the US1J exhibits higher static power consumption, posing a potential risk to system stability and reliability, especially at elevated temperatures. Furthermore, the difference in junction capacitance (25pF vs. 10pF) will affect impedance characteristics at very high frequencies.