Dolly vs zoom
3D Modelling and Animation with Maya
Zoom and dolly are two different tools in Maya which at first appear the same but actually are completely different.
Dolly tool - When you use the dolly tool, the camera moves through the 3D environment and perspective is kept intact.
Zoom tool - When you use the zoom tool, the view cone of the camera is narrowed which makes objects appear closer. This will alter the perspective.
An example of the dolly tool being used in Maya.
An example of the zoom tool being used in Maya.