On Linux distributions, all software is typically "equal" - everything is a package, and the only difference is what repository it comes from.
In BSD, the base system and ports are entirely distinct. The base system is a single coherent unit installed and upgraded as one piece (although the installer allows you to omit some portions of it).
The ports provide additional software packages installed and managed separately on top of the base system. The base system is maintained and patched by the core developers and officially supported by the organization. The ports are provided effectively as a convenience, and are not covered by the same security and maintenance procedures as the base system.
On Linux distributions, all software is typically "equal" - everything is a package, and the only difference is what repository it comes from.
In BSD, the base system and ports are entirely distinct. The base system is a single coherent unit installed and upgraded as one piece (although the installer allows you to omit some portions of it).
The ports provide additional software packages installed and managed separately on top of the base system. The base system is maintained and patched by the core developers and officially supported by the organization. The ports are provided effectively as a convenience, and are not covered by the same security and maintenance procedures as the base system.