The current version of pgsql is 7.0.2 and comes packaged in a file named, surprisingly enough, postgresql-7.0.2.tar.gz. Both of these systems were base installs and no special steps were made to optimize performance. You will find that the process of installation is almost the same on both systems, except for a few steps at the end of the installation process. The same goes for FreeBSD with its ports collection. As with everything in life, there are tradeoffs.
Package managers trade in configuration options for ease of use.
You don't rightly know. You decide which compile time options are set as well as which support elements are included with the install. It may be a good thing to rely on package managers for simpler apps, but when you're talking about server-level systems you want all the control you can muster. When it comes to installation hardware, pgsql is a feature-packed but lean relational database system. Pgsql compiled and ran without complaint on that anemic little machine.