Bryton 40 reading different the my edge 705?

longster

Hi any one had any anything similar I did 1 of my training rides with my new rider 40 and also had my 705 on the bike. At the end of the ride I checked the data and the 40 give RT 2:42 dis 49.53 cal 1700 avg speed 18.3. Garmin RT 2:42 dis 50.49 cals 2427 avg speed 18.69.Altitude gain was the almost the same on both at 4780ft for the bryton and 4810 the garmin.
Thanks mark