title: difference between Linux kernel and UNIX kernel(such as FreeBSD) from programmer's point of view
body: <p>difference between Linux kernel and UNIX kernel(such as FreeBSD) from programmer's point of view.
  I searched several articles about this. They compared these from User's view and Administrator's view also from Company's manager's view.
  Can any body find article or say something from programmer's view?</p>
  
  <p>The programmer I means, both user land programmer or kernel level programmer? </p>
  
  <p>Any hints or enlightenment is really appreciate.  </p>
  
  <p>Wish this is not a cliche question make everybody sick. :P</p>