TRIG versus CAM messages - what causes each

I need clarification regarding the TRIG and CAM messages.

I believe one is the result of the autopilot commanding the shutter - CAM.

And the other one is the result of a hot-shoe pulse indicating the precise time the shutter was released - TRIG

Maybe I have this backwards or wrong in some other way.

If I have it right - will the Mission Planner still geotag images properly when a hot-shoe causes both CAM and TRIG messages to be present?

Thank you!