Walking (auto) and Walking - Differences in calories burned

[AHanley87]

It's probably been asked before, but how come there's such a difference from walking (auto) and selecting walking when counting calories.

Examples:

Walking (auto): 125 minutes / 1013kcal / 7.05 mile

Walking: 120 minutes / 612kcal / 7.72 miles

I presume selecting walking uses GPS and walking (auto) uses movement and guesstimates from height etc and presumes step stride?

But which one is more accurate wise for calorie counting? Online calculators go with walking (auto) calories burned wise.

Basic information:

Height: 6' 3" / 190cm / 75 inches
Weight: 20st 10lb / 290lb / 131.54kg

Any help is appreciated.