How is PostgreSQL for Solaris different from PostgreSQL?
It is not different. PostgreSQL for Solaris is a distribution of PostgreSQL, just as Red Hat is a distribution of Linux. The Sun team adds compiler optimizations, and selects specific additional open source components to bundle with PostgreSQL. We also integrate PostgreSQL with built-in Solaris technologies. 100% of our PostgreSQL for Solaris offering is open source, and 100% of the improvements we make to PostgreSQL are contributed to the PostgreSQL community.