Overview of SQL Server Reporting Services 2012 Architecture, Features, and Tools - Learning SQL Server Reporting Services 2012 - page 134

For example, in the reporting server Kailua in this topic, the service name is
ReportServer$KAILUA . This service has no other dependencies. In fact, you can
access the help file for this service when you look at Windows Services in the
Control Panels shown. In three of the tabbed pages of this window you can
access contextual help.
SharePoint Integrated mode
The following table taken from Microsoft documentation describes the configuration
files used in the SharePoint mode Report Server. Configuration settings are stored in
SharePoint Service application databases.