Scenes speed up your design workflow and keep designs consistent by enabling you to create a re-usable package of layers and effects that can be inserted anywhere in your project.
Each Scene has an independent Canvas and Timeline on which you can create layers and animate properties independent from your main project.
There are 2 aspects to scenes:
Primary Scene - this is the space you edit layers and effects within your scene. Any changes you make to the primary scene will affect all Instances.
Instance - this is the copy of a scene that is added to your projects. Instances inherit all changes made to Primary scenes.
Scenes allow you to create complex compositions while retaining macro-level control over your design. Anytime you find yourself copy + pasting or duplicating elements within your project, consider using Scenes to stay in control and keep your timeline manageable.
When to use Scenes
Scenes and Groups have many overlapping use cases. Here's an Academy video to learn more about when you may want to use Scenes over Groups.