Montana 700i vs fenix 6XS Pro

So today I did a hike that was around 10.7ish miles. I had both my inreach and 6X on. I wanted to test the 6X compared to the 700i. How is it that the 700i has almost 2 more miles on it compared to my fenix? I would have though the 700i is more accurate or at least on par with the fenix. Am I missing something?

thanks