What is a live wallpaper
A Live wallpaper is an animated image that can be used as a background on a phone, tablet or computer desktop. Some live wallpapers can react to touch, be interactive or even be an animation that plays on a loop.
Live wallpapers are usually supported by all phones (IOS, Android, etc.) and computers (Windows, Mac, etc.)
Difference between 3D and Live
Live: contains some type of animation.
3D: image giving the illusion of depth or movement.
Utilization of a live wallpaper can use a lot of energy on your phone, if you want to spare your battery you can disable the animation. Certain wallpapers use more energy than others, but if you have any battery problem or you need your phone battery to last for a longer time, it might not be worth it.
The installation of a live wallpaper is the same as a regular wallpaper. If you need help with the process you can go to these pages: