How accurate is the metadata altitude when it populates automatically?

[P.Donald]

I've noticed when I manually enter lat/long coordinates, the altitude field automatically populates.  I also have noticed that the automatic altitude is about 14' lower than what Google Earth shows for the same coordinates.

Does anyone know which one is the more accurate elevation?

[johnrellis]

Can you post example coordinates showing the issue? I suspect I know what's going on, but an example would clarify.