When I buy scales from different manufacturers I expect the weight showing to be very close. Even wrist based heart readings between different devices are very close these days but when it comes to intensity minutes or Zone minutes on Fitbit there are in my opinion big differences. Both Garmin and Fitbit suggest 150 minutes per week and both seem to use heart rate zones based on age and resting heart rate. However, having used both my Garmin and Fitbit for a week and seeing how they award minutes it seems that Fitbit gives me about two minutes for every 1 minute Garmin gives me. That is a massive difference over the week. I therefore have decided that these measurements just cannot be trusted and if you want 150 activity minutes per week, use Fitbit as you will only have to do half as much effort :-)