Is there a term for the Jedi and Sith?
I mean if you don't know if the person is a Jedi or a Sith, but you know the person is using a lightsaber and has a big knowledge about the force, what a term are you using?
At the broadest definition, you're simply looking for Force Sensitive or Forceful.
If you want to get more specific, and qualify that they are more than just sensitive to the Force, the person can be defined as a Force User ignoring whether or not they belong to a faction. If you want to assign them a grouping based on their allegiance, you might go with Force Adept or Dark Side Adept for Jedi or Sith respectively.
I believe the term Jedi/Sith would be appropriate. And according to star wars rebels, there are things in between.