Alt-Azimuth is the simplest type of mount with two motions, Altitude (vertical) and Azimuth (horizontal): thus the name Alt-Azimuth. Or the shortened name 'Alt-Az'.
The up-down movement changes the instrument’s altitude while the left-right motion changes what’s known as its azimuth. A simple example of an Alt-Az mount is a standard camera tripod. This type of mount is quite easy to use, we recommend it for beginners.
This type of mount is designed to follow the rotating night sky as the Earth turns. An Equatorial mount requires alignment to the Earth's axis (pole to pole). This way you can slowly turn it and objects in the sky will appear to stand still in your field of view. It's definitely a bit harder to use, but for astrophotography this type of telescope mount is the best choice.
When properly aligned with the Earth's poles, equatorial mounts can allow the telescope to follow the smooth, arc-like motion of a star across the sky.
Dobsonian telescopes are Newtonian style telescopes that are mounted on a modified version of the Al-Azimuth mount. Therefore, a Dobsonian mount is a modified Alt-Az Mount. The name Dobsonian really just refers to the mount or base that the optical tube rides on. The design does away with the tripod and complex equatorial counterweight system and gives you straightforward left-right, up-down points of rotation. The simplicity of the design means these telescopes are less costly to manufacture, easy to set up, and all around great instruments for visual observing. If you wish to view deep sky objects on a budget, this style of Telescope for you.
A GoTo Mount simply refers to a computerized mount that automatically point a Telescope at celestial objects that the user wishes to track and view. GoTo mounts can be found in any Mount style - whether it be Alt-Azimuth, Equatorial, Dobsonian etc.
GoTo Mounts will typically come with software that will allow the mount to be controlled by a computer device (such as a remote control, iPad, smartphone etc).