My only interest here is in education, not in bashing any component or technology or user - I hope that's clear.

1000 feet of difference on a 50 mile ride is big enough that you should notice some distinctions in the profile map.
If the elevations at particular points agree with each other then it's a software difference in summing up the totals.
And if the elevations don't match, then it's a measurement difference. This would be especially notable if you rode over any bridges over deep canyons or something like that... or if there were a severe weather change during the ride.