1N4148 vs 1N4001: Which one is better?

A diode is a semiconductor device that allows just one direction of electricity to flow. The current has to flow from the anode to the cathode at all times. The cathode terminal can be identified by a grey bar, as shown in the image above.
The 1N4148 Diode has a maximum current carrying capacity of 300mA  and can withstand peaks of up to 2A. This diode is used in applications that demand fast switching because of its fast recovery time of 8ns at a forward current of 10mA.

The classic 1N4001   power blocking diode is offered in a ten-pack. These can be used for reverse polarity protection (place it between your DC  power jack and circuitry to protect your sensitive electronics from a negative voltage), kickback protection (place it across your solenoids, relays, and DC  motors to safely discharge the spikes generated by the coils), general rectification, and more!
These diodes have a typical voltage drop of around 0.7V and can safely pass 1A continuous current. They also protect against up to 50V reverse voltage. Check out the datasheet for more details!

1N4148 Features

• Fast Switching Speed

• General Purpose Rectification

• Silicon Epitaxial Planar Construction

• Lead-Free Finish, RoHS Compliant (Note 2)

1N4001 Features

• Diffused Junction

• High Current Capability and Low Forward Voltage Drop

• Surge Overload Rating to 30A Peak

• Low Reverse Leakage Current

• Lead-Free Finish, RoHS Compliant (Note 3)

1N4148 2D Model

1N4148 Symbol

1N4148 Footprint

1N4001 2D Model

1N4001 Symbol

1N4001 Footprint

1N4148 Electrical Characteristics

1N4001 Electrical Characteristics

Either of those diodes should work, but the 1N4001  is a better choice because it is the "bigger" device: the 4001 is a 1 amp rectifier, whereas the 4148 is a 100mA little signal device. For small relays, it's fine. 1n4148  is another option. Because the LED begins to conduct considerably earlier than the critical voltage, the critical voltage can never be attained. The 4148 is a diode with a quick recovery time. For logic speed signals, this is useful. A general-purpose diode is the other. The solution, as always, is dependent on your application. The answer is no if you require a large amount of current. The answer is yes if you're using it for battery DC blocking.

1N4148 Package information

1N4001 Package information

Micro Commercial Components Corp. (MCC) is a maker of high-quality discrete semiconductors for consumer applications that was founded in 1991. Diodes, rectifiers, transistors, MOSFETs, voltage regulators, and protective devices are among MCC's products.