Distance discrepancy with Vivoactive 4 an Explorer 2

Until recently, I have been using my Vivoactive 4 to record rides (sync’d with Connect). But now, I also have an Explorer 2 (which also sync’s with Connect). The problem is that the ride distances do not match (e.g. over a 50 mile ride, there is a 1 mile discrepancy). Is this to be expected? Or is there some ‘tuning’ of the GPS on one or both that I can perform to bring them in line?

Thanks in advance.