The AOS connects to the Microsoft Dynamics AX database to process transactions.
The AOS connects to the model store to display application elements such as forms and reports.
The baseline database contains a model store that is used to upgrade X++ code to Microsoft Dynamics AX 2012. The baseline database is used to analyze application updates before they are applied.
Reporting services database. You store your SSRS reports here.
Model store database
The model store is the database where all application elements for Microsoft Dynamics AX are stored. Customizations are also stored in the model store. The model store replaces the Application Object Data (AOD) files that were used in earlier versions of Microsoft Dynamics AX.
Baseline model store
The baseline model store holds model store tables for the earlier version of the metadata and is used only during upgrade. The baseline model store is like the old folder in earlier versions of Microsoft Dynamics AX.
Note : In Microsoft Dynamics AX 2012 R2, the model store was moved into a database that is separate from the business database.
Just to complement. ReportServer And ReportServerTempDB aren’t related directly to an AX installation, those db’s are created during the installation of reporting services.