Clone, Knockoff, Counterfeit?

What's the difference in usage of Clone, Knockoff, Counterfeit?

The word clone has a pejorative connotation in my mother tongue, that was the source of my question.

as far as I understand:

  • a Clone is a (functional) copy from which it is clear it is a copy (e.g. different logo)
  • a Counterfeit is a (identical) copy which is sold for the real thing
  • a Knockoff is ??

robtillaart:
a Knockoff is ??

To me a knockoff is the same as a counterfeit but sold at a cheaper (clone) price so you think your getting a bargain.

A Knock Off, for all intense purposes, Has the appearance of a Clone or Counterfeit item, but the internals

a) Are Junk
b) Only Partly Work
c) All of the above