The 1N4001 is a 50V, 1A standard recovery rectifier diode in a DO-41 axial leaded package. It features a forward voltage of 1.1V and a reverse recovery time of 1.5µs.
The 1N4002 is a 100V, 1A standard recovery rectifier diode from Diotec Semiconductor in a DO-41 through-hole package. It features a forward voltage of 1.1V and a reverse recovery time of 1.5µs.