Reference: https://www.cisco.com/c/en/us/support/docs/security/firepower-ngfw/212330-firepower- management-center-display-acc.html

Intrusion events provide the detection evidence needed to understand which signatures fired, the affected source and destination addresses, event severity, protocol information, and other indicators associated with the suspected compromise. Host connections provide the corresponding network context, allowing the analyst to determine which systems communicated, when the sessions occurred, and which ports, applications, or protocols were involved. Together, these details connect security detections with the traffic flows that produced them and support reconstruction of the incident. Client applications by user and user connections are useful when the investigation is primarily identity-focused, but they do not provide the same direct combination of exploit evidence and host-level network activity. The number of attacked machines is an aggregate measurement and lacks the granular information necessary to investigate the suspicious communications and determine their cause.

Reference: https://www.cisco.com/c/en/us/td/docs/security/firesight/541/user-guide/FireSIGHT-System- UserGuide-v5401/Reports.html#87267