SSRS- database and Report Server - can they be different?
Yes, the report server can be installed on another machine than the server where the databases reside, there can even be more than one report server instances connected to the same reportserver database (this is called scale out deployment).


  Two or more report server instances sharing a single report server database. 


You can run

exec ListInstallations 


In the reportserver database to list the Report servers connected to this database.