This article provides detailed explanations of the Risk Reports available in PPO:
The report includes all the fields on the Risks entity for all risk records and projects. If the “Include Project Information” checkbox is selected, the report will also include all the fields on the project entity.
The Risk History Report shows when the risk was updated, by whom and what the recent risk action/response was. This provides a complete view of how the risk has changed over the lifespan of the project.
The Risk Report shows all the current risk information (no history records are shown on this report).