Hi Franzmann,
First of all, you need to know what is an Activity.
An activity can be thought of as any action for which an entry can be made on a calendar. You can create activities for yourselves, can assign them to someone else, or can share them with other users or teams.
1. What are the advantages and disadvantages of the Normal entity and the Activity entity?
- Normal entity is only viewable/usable to the users with corresponding security roles while Activity entity is available to users who have access to other activity entities.
For example, the privileges of Account entity are granted separately in the following screenshot. And the privileges of the activity entities are uniformly granted.

- The activity entity can directly use some existing fields in the Activity, such as Start time, so it does not need to customize a lot of things to record the information you need. However, the predefined fields of Activity entity itself cannot be modified

- They cannot be converted to each other after they have been created.

2. When should you use which entity?
This is determined by the definition of the Entity.
You may consider setting it as an Activity in the following situations.
- It can be determined as an action for which an entry can be made on a calendar.
- It will definitely have one or more attendants.
- It has the activity-specific characteristics, including start time, stop time, due date, duration, description, subject and so on.
- It has the activity-specific states, including Opened, Canceled, Completed.
- There is NO security requirements now or in the future.
- It will be shown in the timeline of the attendants.
Here are some simple examples of which entities can be created as Activity entities, such as Meetings, Projects and so on.
Hope this will help you.
Nya