Honestly, I do not know. Both has the same helix antenna.
On the move, some time the 60 show better accuracy, but next turn the 76 win back and vice versa.
I guess the angle of mount, line of sight, unit placement near certain metallic object could play some part.
Overall, both seems to perform equally well.
PS. It would be take the fun away (geocaching game) if they show exactly the same location.
Cheers,
Joel