Difference between Check Airman and Instructor Pilot
As a check airman (Part 135) you are administering a 135.293, 135.297 or 135.299 check. You are filling an 8410-3 form and that check makes the pilot "current" per the FARs
As an Instructor Pilot you teach systems, normal/emergency procedures, IOE, 61.55 training etc.. but you are not performing a 135.293, 135.297 or 135.299 check. If you were filling a 8410 form you were a Check Airman otherwise you are not. To become a check airman you must have taken a checkride with an FAA inspector who observed you performing a checkride.
So, as a company Check Airman you are peforming checkrides and as an Instructor Pilot you are instructing and/or giving pilots initial experience.
If you are asking the question I would guess that you were not but only you would know.
Hope that clears it.