Oh, so Kaan would beat Revan or Malak? I doubt it.
Technically there is only one difference. Sith belong to the organisation called 'The Sith'.
You aren't born a Sith. You don't learn to be a Sith. You join them. If you join up with the group called 'The Sith', then you are a Sith.
You can then make plenty of assumptions and logical workings about teachings and techniques that those in the Sith might have access to that others would not. But the literal difference is still the same. And of course, all Sith ARE Dark Jedi as well; the terms are not exclusive.
Meanwhile, of course Revan and Malak were Sith Lords; that's the entire set-up.