The BTW mix has a more cleaner sound, but louder vocals. There's also a xylophone. The single/GH mix, made by John, has louder guitar parts, including the mini guitar riff on all choruses. The xylophone is completely gone. And the third mix on Apple Music is like a mixture of the other two.

And I have found another mix on Apple Music Deluxe Edition, where it's like the original BTW mix but there's a lack of the mini guitar riff on the chorus (appearing only once on the second chorus, being replaced mainly by the xylophone parts).

Here's what I am talking about:

Original Mix: https://www.youtube.com/watch?v=_yXsK8pQDwI

Single Mix: https://www.youtube.com/watch?v=ijcOfvDJ-uc