| S.N. | Valve | Transistor |
| 1. | Also known as vacuum tube or electron tube or tube, valve is a device that controls the flow of electric current in a high vacuum between electrodes to which an electric potential difference has been applied. | Transistor is a semiconductor device with three terminals that amplifies or switches electronic signals and electrical power. |
| 2. | Electrons are the charge carriers in a valve. | In n-type transistor, the charge carriers are electrons whereas in p-type, holes are the charge carriers. |
| 3. | Charge carriers (mobile electron cloud) are generated by heated metal cathode, a process called thermionic emission. | Charge carriers are released by emitters. No heating element is required. |
| 4. | It is not so efficient because large power in wasted in heating. | It is more efficient than valve since there is no wastage of power through heating. |
| 5. | A valve needs a high power source of a few hundred volts. | A power source of a few volts is sufficient. |
| 6. | It requires a vacuum on its construction. | It doesn’t require vacuum on its construction. |
| 7. | A valve doesn’t work instantaneously when switched on since time is required for the cathode to get heated. | It works instantaneously when switched on. |
| 8. | Comparatively it has a bigger size and more weight due to which it has limited applications in electronics. | It has a small size and less weight due to which it is widely used in modern electronic appliances. |