1. Gate Trigger Voltage (Vgt): The maximum Vgt of the T1210T-8T (1.3V) is lower than that of the BTA312-800ET (1.5V). This makes the gate of the T1210T-8T more "sensitive," requiring a slightly lower drive voltage. Consequently, in circuits with significant electrical noise, the T1210T-8T carries a marginally higher risk of spurious triggering due to voltage transients. 2. Non-Repetitive Surge Current (Itsm): Under 60Hz conditions, the BTA312-800ET has a higher surge current rating (105A) compared to the T1210T-8T (95A). This indicates that the BTA312 offers a greater margin against transient overloads (e.g., motor startup, capacitive inrush currents), potentially leading to better long-term reliability. 3. Datasheet Specification: The BTA312 datasheet only specifies the maximum junction temperature (Tj), whereas the T1210T explicitly states the full operating temperature range (-40°C to 150°C). This discrepancy typically does not reflect an actual performance difference, as the TO-220AB package technology supports this range for both parts. It is more likely a variation in manufacturers' documentation practices. Nevertheless, for design purposes, the explicitly stated range of the T1210T should be used as the basis.