Headphones are essentially a set of tiny speakers that sit in, on or around your ears and like all speakers, they have drivers. Everyone can agree that not all headphones are the same or created equally. But besides the superficial differences and the various features you may be offered such as noise cancelling and wireless capabilities, there are other more subtle differences that can make a huge difference. That subtle difference is determined by the type of driver used in the headphones.
The driver is what makes or produces the sound you hear and is the most important part of the speaker. One can assume; the better the driver, the better the sound, and the more powerful the output. It is the part of a speaker that compresses and refines air to create sound waves, and the type of driver used will dramatically impact the sound quality of a pair of headphones. The driver unit falls in the range of 8mm to 15mm for earphones and 20mm to 50mm for headphones.