Key Differences Between Diode and Transistor

1. The diode is a semiconductor device which allows the current to flow only in one direction, whereas the transistor transfers the resistance from the low resistance region to high resistance region.
2. The diode is used for converting the AC to DC or for rectifications whereas the transistor is mainly used for amplification and as a regulator.
3. The diode has two terminals namely anode and cathode.The anode is the positive terminal, and the cathode is the negative terminal of the diode. The transistor has three terminals; they are the emitter, collector and base.
4. The diode is a type of uncontrolled switch whereas the transistor is a controlled switch.
5. The transistor is mainly classified into two types, i.e., the Bipolar junction transistor and Field Effecting Transistor. The BJT uses both the electrons and hole as a charge carrier, and the FET is a unipolar transistor. The diode has many types, for example, photodiodes, Zener Diode, Tunnel Diode, Varactor Diode, etc.
6. The P-type and N-type is the two region of the diode. The hole is the majority charge carrier of the P-region and electrons is the majority charge carrier of the N – region of the diode. The transistor has three regions, namely emitter, base and collector. Among the three regions, the base is the smallest region, and the collector is the largest region of the transistor.
7. The diode has only one depletion layer between P – type and N – type whereas the transistor has two depletion layer, one is between emitter and base region, and the other is between the base and collector region.

Basis For  Comparison

	Diode	Transistor
Definition	A semiconductor device in which current flows only in one direction.	A semiconductor device which transfers the weak signal from low resistance circuit to high resistance circuit.
Symbol
Uses	Rectification	Regulator, Amplification and Rectification
Terminal	Two (Anode and Cathode)	Three (Emitter, Base and Collector)
Switch	Uncontrolled	Controlled
Types	Junction diode, Light emitting diode, Photodiodes, Schottky diodes, Tunnel, Veractor and Zener diode.	Bipolar transistor and Field Effect Transistor.
Region	P-region and N-region	Emitter, Collector and Base
Depletion Region	One	Two