Speaker & Headphones

Speaker:

A speaker is a term used to describe the user who is giving vocal commands to a software program.
A computer speaker is a hardware device that connects to a computer to generate sound. The signal used to produce the sound that comes from a computer speaker is created by the computer's sound card.

Figure: Speaker

Headphones:

Sometimes referred to as earphones, headphones are a hardware output device that either plug into your computer line out or your speakers to privately listen to audio without disturbing others.

Figure: Headphones