1. Reverse Recovery Time (trr): This is the fundamental performance gap. The 1N4002 has a trr of 2 µs, classifying it as a standard‑recovery diode, whereas the RGP10B features a trr of 150 ns, making it a fast‑recovery diode. At the instant of circuit switching (turn‑on/turn‑off), the 1N4002 requires a significantly longer time to clear the stored charge from its conduction period before it can block reverse voltage. In high‑frequency switching circuits (e.g., switch‑mode power supplies (SMPS), high‑frequency inverters, PWM drives), an excessively long trr causes large reverse‑recovery current spikes and substantial heat generation during turn‑off. This severely degrades efficiency and can induce electromagnetic interference (EMI) or even thermal runaway. The fast‑recovery characteristic of the RGP10B is specifically designed for such high‑frequency applications. 2. Forward Voltage Drop (Vf @ 1A): The RGP10B (1.3V) is higher than that of the 1N4002 (1.1V). At the same 1A current, the RGP10B incurs higher conduction loss (approximately 0.2W more), leading to more pronounced self‑heating. This is a typical trade‑off in its semiconductor structure to achieve fast recovery. In applications demanding high efficiency or with limited thermal headroom, this is a disadvantage. 3. Series Positioning: The 1N4002 belongs to a general‑purpose “standard” series; the RGP10B is part of the “SUPERECTIFIER®” series. This is not merely a trademark distinction but reflects different design optimization goals. The SUPERECTIFIER® series generally focuses on improved switching characteristics (e.g., trr, soft recovery), sacrificing some forward voltage for superior dynamic performance suited to high‑frequency operation. The 1N4002 series, in contrast, is optimized for basic rectification with low cost and high reliability. Summary: The significant price difference stems from their fundamentally different performance targets. The 1N4002 is an economical line‑frequency rectifier, while the RGP10B is a fast‑recovery diode intended for high‑frequency switching applications. Any substitution decision must be based on the circuit’s operating frequency and switching requirements, not solely on voltage and current ratings.