1. Certification: The BC847BH RFG is explicitly marked with "Grade: Automotive" and "Qualification: AEC-Q101," whereas the BC847B RFG carries no such designation. The BC847BH RFG is a version qualified to the automotive reliability standard AEC-Q101. This qualification requires the device to pass a rigorous series of stress tests (e.g., temperature cycling, H3TRB, ESD) to ensure stable operation under the extreme temperatures, vibration, and long-term reliability demands of the automotive environment. Although the BC847B RFG shares the same operating temperature range (-55°C to 150°C), it has not undergone this systematic certification. Its long-term reliability and failure rates in automotive applications remain unverified. 2. Price Difference: The unit price for the BC847BH RFG is $0.21000, compared to $0.16000 for the BC847B RFG. This price differential primarily stems from the additional testing, control, and production costs associated with automotive-grade qualification. The selection must balance reliability requirements against cost. Summary: Both parts share identical core electrical parameters and package. The fundamental difference lies in "whether they possess the reliability certification required for automotive electronics." They are interchangeable in general-purpose fields such as consumer and industrial applications. In automotive-grade designs, the BC847BH RFG is mandatory, while the BC847B RFG does not meet the entry requirements.