1. Dynamic Performance (fT): The transition frequency of the 2SCR293P5T100 (320 MHz) is significantly higher than that of the 2SD1664-R-TP (150 MHz). The former offers superior response speed and reduced phase lag in high-frequency switching or amplification circuits, making it suitable for higher frequency operation. The latter is confined to mid-to-low frequency scenarios. 2. Static Performance (hFE, Vce(sat)): The 2SCR293P5T100 features higher DC current gain (270 vs. 180) and a lower collector-emitter saturation voltage (under more stringent test conditions). At an equivalent operating point, the former is easier to drive and exhibits lower conduction loss, contributing to improved circuit efficiency. This is particularly beneficial in low-voltage designs or those requiring drive margin. 3. Leakage Current (ICBO): The collector cutoff current of the 2SCR293P5T100 (100 nA) is lower than that of the 2SD1664-R-TP (500 nA). This suggests potentially superior PN junction quality or manufacturing process for the former, leading to better leakage control in the off-state within high-temperature or high-impedance circuits. For most switching applications, however, this difference is negligible. 4. Operating Temperature Range: The 2SD1664-R-TP explicitly supports a full military-grade temperature range down to -55°C. In contrast, the 2SCR293P5T100 datasheet only specifies a maximum junction temperature (Tj). The former offers guaranteed reliability in extreme low-temperature environments. Using the latter at -55°C may require additional verification against its specifications or testing. 5. Cost & Market Positioning: The nearly 7x price difference reflects their distinct positioning. The 2SCR293P5T100 is a high-performance, high-reliability component (likely due to brand premium and advanced process). The 2SD1664-R-TP is an aggressively cost-optimized device, suitable for applications with extreme cost sensitivity and relaxed performance requirements.