Garmin GPSr or iPhone- which coords?

[SFTA2010]

Wally and our dog and I looked unsuccessfully on Sunday for the Shore Path cache in Bar Harbor. The Garmin Rino130 took us to the coordinates, and so did the iPhone. The problem-- those lat/long readings were in two different spots, not even within sight of each other. And of course both places had maple trees and rocks. But the Garmin spot was not on the ocean side of the trail.
How do you know which set of coordinates are correct? The Garmin showed signals from at least 4 satellites; the iPhone didn't give me that info.
Sorry I was not able to get into the chat tonight. I appreciate the help, but I'm not familiar with a lot of the computer terms and procedures. I've tried to do an attachment to this message, just to see if I can make that work.
SFTA2010