The programs needed to create and run a PostgreSQL server
PostgreSQL is an advanced Object-Relational database management system (DBMS). The postgresql-server package contains the programs needed to create and run a PostgreSQL server, which will in turn allow you to create and maintain PostgreSQL databases.
acquired package info from repodata DB: repodata/91b6af401655a285db1e90125f33be6c71af360b3b8b923fa05b21449c036c08-primary.sqlite.bz2
The test suite distributed with PostgreSQL
The postgresql-test package contains files needed for various tests for the PostgreSQL database management system, including regression tests and benchmarks.
Extension modules distributed with PostgreSQL
The postgresql-contrib package contains various extension modules that are included in the PostgreSQL distribution.
PostgreSQL development header files and libraries
The postgresql-server-devel package contains the header files and configuration needed to compile PostgreSQL server extension.