So, many of us who start to learn about headphones or headsets come across these two words or in some cases they are called as Active Noise Cancellation and Passive Noise Cancellation.
Let me explain in clear of what actually these mean.
Noise Isolation or Passive Noise Cancellation
This is the term generally used where, not any additional technology is employed to stop external noise from disturbing your music. In other words, these type of headphones stop external noise from your music with their design by forming a wall between outer sound and your music. The headphones of this type stop air from entering into your ears utmost. These provide a good choice for those who want to stay in touch with external world along with their music.
Noise Cancellation or Active Noise Cancellation
These are the exact opposite versions of the previous mentioned type. These have additional technology employed to block the external world from disturbing your music. These type of headphones or headsets have specially powered mic and speaker along with the ones faced towards your ear. This additional setup is to get external noise through mic, process it and then release a wave opposite to the sound outside so that both of them neutralize finally reaching nothing to your ear. They completely remove the noise around you or at most they try their best.
The downside with this technology is the waves produced to cancel the external noise are seemed to disturb some of the eardrums that were highly sensitive leading to some disorders and as they have additional technology employed. They require power to drive them and these are generally a bit heavier than the normal ones.