1. Maximum Power Dissipation (Power - Max): The PMBT3906YS,115 is rated for 350mW, while the MBT3906DW1T1G is rated for 150mW. Under identical operating conditions, the Nexperia device can withstand more than twice the power dissipation, offering greater thermal design margin and enhanced long-term reliability. When substituting, the junction temperature under actual operating conditions must be re-evaluated to ensure it remains within limits. 2. Qualification and Certification: The PMBT3906YS,115 is explicitly marked as compliant with AEC-Q101 and classified as "Automotive" grade, indicating that its materials, processes, and testing meet automotive electronic reliability standards. The MBT3906DW1T1G does not carry this certification; although it features a wide operating temperature range, there is no official commitment to automotive-grade validation. Consequently, the former can be used directly in harsh environments such as automotive applications, while the latter poses qualification and reliability risks in such scenarios. 3. Operating Temperature Range: The MBT3906DW1T1G specifies a full temperature range (–55°C to 150°C TJ), whereas the PMBT3906YS,115 only indicates the upper limit (150°C TJ). The practical impact is limited, as both share the same maximum TJ and typically meet commercial/industrial lower-temperature requirements. However, the full-range specification provides explicit assurance for designs involving extreme low-temperature conditions.