title: what is difference between multiprocessing and parallel processing?
body: <p>This question might be a duplicate question.</p>
  <p>Like I understand during Parallel processing, CPUs/cores work on a single task(program or process) to make total execution time shorter, and during multiprocessing CPUs/cores, work on a completely different task (tasks don't have anything in common), this is done to make total execution time shorter. Am I right?
  I also have another question: if multiprocessing or parallel processing makes the program faster why we don't use it every time?</p>