$Id: ports-v-packages.php 297 2009-12-30 01:49:46Z gjb $

ls /var/db/pkg/*

The 'ports' tree is a list of software with a customized Makefile, located in the /usr/ports directory. Ports are (typically) updated regularly, and usually have the "latest and greatest" software.

Packages are compiled once, when the -RELEASE version of FreeBSD is released.

What this means using Xorg, FreeBSD 6.2-RELEASE, and FreeBSD 6.3-RELEASE as examples: When FreeBSD 6.2 was released, the stable version of Xorg was 6.9. If you wanted to get Xorg installed, but not compile it yourself, you could run:
pkg_add -r xorg
which would install Xorg 6.9.

At the time of this writing, the stable release of Xorg is 7.3. So, if you did 'pkg_add' in FreeBSD 6.3, you would install the 7.3 version of Xorg.

Using ports, in 6.2-RELEASE, if you
cd /usr/ports/x11/xorg
make install clean
you would compile the 'latest stable' version of Xorg, which would be 7.3