1. Reverse leakage current (IR): The STR40100LCT is rated at 100 µA @ 100 V, whereas the SDT40A100CT is specified at 120 µA @ 100 V. Under the same high-temperature reverse bias conditions, the SDT40A100CT exhibits a slightly higher static power dissipation (approximately 20% increase), which may have a minor impact on system efficiency and temperature rise. However, this deviation is generally acceptable in most industrial-grade applications. 2. Manufacturer package designation: The STR40100LCT is labeled as TO-220AB, while the SDT40A100CT is marked as TO-220-3. Both refer to the same physical package (JEDEC TO-220-3); the difference is only in the manufacturer’s internal coding. Mechanical dimensions and pinout are fully compatible, with no practical installation differences.