What is the difference between noise-canceling and noise-isolation headphones? Which is more effective?

Answer 1

Because the cancelling effect used alone cannot be perfect, the noise-isolation method works the best.

There are some headphones that use BOTH techniques - over the ear for isolation and active cancelling for remaining lower frequency noise that is hard to block. These are the best. I haven't spent the $300, but I tried a friend's pair - the Bose over the ear noise cancelling are amazing.

Answer 2

A noise canceling headphone has a microphone and an electronic circuit to pickup and feed a signal to the speaker inside the headset. The phase is reversed electronically which effectivly cancels the outside noise. These sets have a battery inside them to power the electronics.

Noise Isolation type headphones work the same way an ear protection to block outside noise. They are either soft foam that fits in the ear or the large over the ear cups. They are totally passive - No electronics - and are quite effective. They do bother some people who do not like plugs in their ears though.