1. Switching Speed and Reverse Recovery Time (trr): Difference: The S1GT-04LC-F is a fast recovery diode (trr ≤ 500 ns), whereas the S1G-13-F is a standard recovery diode (trr = 3 µs). The recovery time of the latter is approximately six times longer than that of the former. In switching circuits, the standard recovery diode generates substantially higher reverse recovery current and charge compared to the fast recovery type during turn-off. This results in a sharp increase in switching losses—particularly in the switching transistor—reduced system efficiency, and the potential for severe electromagnetic interference (EMI) and device overheating. This parameter is the primary factor determining the application boundaries between the two diodes. 2. Package and Thermal/Physical Characteristics: Difference: The S1GT-04LC-F is housed in an SMB (DO-214AA) package, while the S1G-13-F uses an SMA (DO-214AC) package. The SMA package typically has slightly larger physical dimensions and lead sizes than the SMB. The SMA package generally offers marginally better thermal dissipation capability. However, this does not represent a performance upgrade but rather a difference in physical compatibility. Substitution requires reevaluation of PCB layout, pad design, and heatsinking space, as the two packages are not footprint-compatible. 3. Application Positioning and Cost: Difference: Based on the speed difference, the S1GT-04LC-F is intended for high-frequency switching applications, while the S1G-13-F is positioned for low-frequency rectification or general-purpose use. The latter is priced at roughly half the cost of the former. The price difference directly reflects the cost associated with performance (switching speed). When considering substitution, cost alone should not override the performance requirements; otherwise, total system cost may increase due to efficiency losses and reliability issues.