The biggest difference between a Linux install and a FreeBSD install is that applications are completely separate from the base OS. There is only 1 ports tree, giving you a "rolling release" for applications ... without changing the base OS.
For example, you can install FreeBSD 8.2, install the ports tree off the CD, install Firefox 3.x via that ports tree, then later update the ports tree and upgrade to Firefox 4.x, without changing the base OS version.
Using binary packages, things are a bit different. If you install FreeBSD 8.2 and use
pkg_add(1) to install packages, even if you install packages 6 months later, you get the same versions for apps. This is because binary packages for a specific FreeBSD release are created when the install CD is made, and generally aren't upgraded.
However, binary packages for FreeBSD 8-STABLE (the development branch that will eventually become the next -RELEASE, similar to the way Debian Testing works) are built on a roughly monthly basis. So, if you install FreeBSD 8.2, change the
PACKAGESITE environment variable to point to the
packages-8-stable directory on the FTP servers, then you get a "mostly rolling release" for applications. But, the versions available in binary package will be behind the versions available in the ports tree.