1. Reverse Voltage & Leakage Current: The MBRF20200CTG offers a higher reverse voltage (200V), providing greater design margin. However, its reverse leakage current at rated voltage (1 mA) is significantly higher than that of the STPS20170CFP (15 µA). Under high-voltage operating conditions, the MBRF20200CTG will exhibit greater static power loss, potentially leading to higher operating temperature rise and imposing more stringent requirements on thermal design. 2. Junction Temperature Range: The STPS20170CFP has a higher maximum junction temperature (Tj max) of 175°C compared to 150°C for the MBRF20200CTG. This grants the STPS20170CFP greater thermal headroom and higher reliability in harsh thermal environments. This difference is critical for compact or thermally constrained designs. 3. Performance Focus: The STPS20170CFP is superior in leakage current and junction temperature parameters, reflecting its emphasis on efficiency and reliability in high-temperature environments. The MBRF20200CTG trades off higher leakage current for higher reverse voltage. Its SWITCHMODE™ series designation indicates a stronger focus on high-frequency switching performance and voltage margin in switched-mode power supplies, where its leakage current level is generally acceptable. Substitution Recommendation: Substitution is typically feasible in applications such as switch-mode power supplies (e.g., PFC, flyback topologies) where operating frequency is high, voltage margin is prioritized, and thermal conditions are favorable. In applications extremely sensitive to efficiency and temperature rise, or those with high ambient temperatures, substitution requires caution, and thermal design should be re-evaluated.