1. Continuous Forward Current (Io): The RS3GB is rated for 3A, while the MURS340S is rated for 1.5A. This is the most fundamental difference. The MURS340S cannot sustain the same continuous operating current as the RS3GB. A direct replacement could lead to thermal overstress and failure of the MURS340S. It is essential to verify that the actual operating current in the circuit is significantly below 1.5A with sufficient design margin. 2. Reverse Recovery Time (trr): The RS3GB has a trr of 150ns, compared to 75ns for the MURS340S. The MURS340S offers twice the recovery speed, which can reduce switching losses and noise in high-frequency switching circuits (e.g., PFC stages, flyback snubbers), resulting in superior performance. 3. Maximum Operating Junction Temperature: The RS3GB is rated for 150°C, while the MURS340S is rated for 175°C. The higher temperature rating of the MURS340S provides greater reliability margin in high-ambient-temperature environments or applications with constrained thermal design. 4. Forward Voltage Drop (Vf): Under the same 3A test condition (Note: this exceeds the MURS340S rating), the maximum Vf for the RS3GB is 1.3V, compared to 1.45V for the MURS340S. This indicates that when operating near its rated current, the MURS340S will exhibit slightly higher conduction losses, exacerbating thermal concerns.