A zoom is technically not a camera move as it does not require the camera itself to move at all. Zooming means altering the focal length of the lens to give the illusion of moving closer to or further away from the action.
The effect is not quite the same though. Zooming is effectively magnifying a part of the image, while moving the camera creates a difference in perspective — background objects appear to change in relation to foreground objects. This is sometimes used for creative effect in the dolly zoom.
Zooming is an easy-to-use but hard-to-get-right feature of most cameras. It is arguably the most misused of all camera functions. See our camera zoom tutorial for more information.