Dear Arief,

as you can see your questions are not very welcome on the mailinglists, therefore i advice you to have a look at this book if you are interested in BSD's technical background

Title: The Design and Implementation of the 4.4BSD Operating System

Authors: McKusick, Bostic, Karels and Quarterman
Publisher: Addison-Wesley

4.4BSD is what NetBSD, OpenBSD and FreeBSD are basing on.

For Linux i cant help you.

Take this approach to read about technicals issues yourself, by finding the differences yourself you learn much more than being told.

greets, josef