Generally agree with the above, sometimes it's best to use different terminology to reduce confusion (a bit like the great "Engineer" debate). Here's a suggestion only, loosely based upon UK practice and which would at-least be understood in my office and I suspect most equivalents.
Assessing pilot - pilot currently undertaking the assessment of an aircraft under any circumstances.
Check Flight - confirmation in flight that an aircraft is behaving as advertised (typically post-maintenance)
Check Pilot - Pilot qualified to conduct a check flight, currently known in RAF parlance as a UTP.
Examiner - Pilot qualified to assess another pilot.
Examining pilot - pilot currently undertaking the assessment of another pilot under any circumstances.
Flying Test - flight for purposes of assessing a pilot's competence.
Test Flight - a flight in which an aircraft is being assessed for data that doesn't currently exist. This has two versions "experimental test flight" and "certification test flight".
Test Flying - the general practice of assessing aeroplanes.
Test Pilot - Pilot qualified to conduct a test flight. Generally assumed that such a person is also de-facto a check pilot.
Note that I've specifically avoided the term "flight test", it's just too open to misinterpretation and is used in too many contexts.
G