The gap between FreeBSD and Linux has closed over time and the underlying kernels are similar
in many ways. Some people will say that a web stack running on FreeBSD will have better
performance as the scheduler favors this type of processing.
With the Linux kernel being highly configurable I can assume that similar results can be
achieved and that purpose built distributions already have a tweaked kernel to serve their
purpose.
Linux itself is GPL licensed and FreeBSD is BSD licensed. You can take a look a the following
to understand the difference:
http://www.matusiak.eu/nu ...FreeBSD comes with a base of tools, where as Linux is just the kernel. I don't think this
should worry you too much unless you wanted to roll your own distribution.
Typically you can find commercial applications available for Linux but generally less
available for FreeBSD.
What are you wanting the OS to do?