The pick-ups are the most important part of the guitar. They can make the guitar sound its best or worst. If cheap pick-ups are put into a $2,000 guitar it won't sound any better than a $125 guitar. Expensive pick-ups give off a superior sound in richness and in tone. The notes will be clearer and louder from a very expensive pick-up. The pickup on the left is a humbucking pick-up, which means that it uses two pickups for one set of wires. The one on the right is a single coil pick-up and is the most commonly used.

Both pictures from www.Carvin.com