title: OS - Difference between Scheduling Algorithms (RR, SJF...) and PCS or SCS
body: <p>I'm learning about the Operating System concepts. 
  There's one thing I don't understand well regarding scheduling process and thread. </p>
  
  <p>Process Scheduling algorithms (SJF, RR...) is a general term, which means that these algos are also used for Thread Scheduling.</p>
  
  <p>However, it exists also PCS (user-level) and SCS (kernel-level) mechanisms for Thread Scheduling.</p>
  
  <p>So what is the differences between SFC,RR...and SCS (or PCS) ?</p>
  
  <p>Thank you very much. </p>