While often used interchangeably, in some areas or jurisdictions they can have varying meanings. When filing a car accident claim, it's important to know at least the broad definition of each.
An incident report is a statement from a victim of a car accident or a crime. A 911 call or non-emergency call to a police station or paramedics can be considered an incident report.
A police report is a detailed description of a car accident or crime as written by the officer who responded to the scene. As these are are sworn statements written and signed by government officials, generally the police report is the one used in car accident settlement negotiations. However, recordings of 911 calls and other, less formal incident reports are also utilized by insurance claims adjusters and juries when trying to uncover the facts of the case, determine who was at fault in the crash, etc.