What is the difference between AEC (Acoustic Echo Cancelation), and NC (Noise Cancelation) ?

What is the difference between AEC (Acoustic Echo Cancelation), and NC (Noise Cancelation) ?

AEC or Acoustic Echo Cancelation is a function to prevent the Far End of a conference call (ATC or VTC) from hearing themselves echo back to them. It is caused when the Far End audio comes in to the local room speakers and is picked up by the microphone and sent back to the Far End. NC or Noise Cancellation is a function to reduce or eliminate room noise and machine noise. This is typically constant, low level noise picked up by the microphone and caused by electronic equipment, HVAC, cars and noise from outside, Etc. This does not include papers shuffling or people having side conversations in a room as those are not a constant.