> 1- Why BSD is created?
Why not?
> 2- what difference between BSD and Linux is exist?
Long story.
> 3- What BSD distro is good for PC?
There is no such thing as BSD distro.
FreeBSD, OpenBSD and NetBSD are independent projects, they develop the kernel and userland programs independently. In most cases, we call them BSD-branch instead of BSD distro.
In contrast, Linux distros share the Linux kernel and GNU userland programs. In most cases, we call them Linux distro or Linux distribution
> 4- can i run Linux software under BSD?
In general, there is no such thing as Linux software. Most of the existing Unix software are portable. In other words, they are not limited to one Unix-like OS.
However, there do exist some software that is designed for Linux.
My suggestion is you should google or wiki the following terms: Unix, Unix-like, kernel, userland, Linux, GNU, BSD, BSD-branch...