Accuracy of Runn in Zwift

This past weekend, I compared the Stryd to Runn unit on Zwift at the same time. I was surprised at how different the results were between the two. Runn is calibrated with Zwift and my Stryd isn't (and they claim shouldn't be). I would expect some difference, but I think this is a bit too much. Any ideas here? Which should I trust from a distance standpoint? 

Runn: https://www.strava.com/activities/3506361230

Stryd: https://www.strava.com/activities/3506358545