A list is a view of type report that has been flagged as a list. Lists are used throughout the platform when displaying data in tabular form and they can be managed both directly where they are displayed using the Lists > List management context menu or they can be built from Forms & Views.
To flag a report as a list you must check Available as list / print / dashboard and Available in the backoffice in the options. This ensures that the list is selectable from the left context menu when viewing tabular data. If you create a list directly from the Lists > List management context menu then the flags are set automatically.
The designer layout for lists is exactly the same as the layout used when designing a report view.