Apple Music Tethering problem

[purpleparrotuk]

I have done a test and have some very weird results. Using my iphone 4s tethered to my Nexus 6, 5 minutes of music played from Apple Music uses approx 50mb (ridiculous)! But my 4s tethered to an Iphone 6s only uses 10mb of music. Can someone please help clarify why the big difference? (both on the same cellular network). Only doing this until Android version is out.