Before we start with the definition of dynamic dashboards, let's understand whether there is a concept of a static dashboard. Yes, there is, but it is not called a static dashboard. So, there are two types of dashboards in Salesforce--normal dashboard and dynamic dashboard.
In summary, here is the difference between normal and dynamic dashboards:
| Description | Normal dashboard | Dynamic dashboard |
| Viewing user | Viewing user is defined on dashboard creation, users cannot change the viewing user when opening the dashboard | Viewing user is the user who opens the dashboard. The user is able to change the viewing user (the user needs to have additional permission and the dashboard needs to be configured) |
| Number of dashboards | No limitation | There is a limit to the number of the dynamic dashboards, this limit is based on the edition subscribed |
| Permissions... |