the difference is the detail of the image. id say get the hero one. the reason is that you are most likely not using the gopro to make serious editis, and if you are making serious edits why would you get a gopro to do it with
1080p one shoots 720- at 60 fps which is what you wanna film in for skiing, since you can make better slow motions with that footage compared to the 960p gp which only films 720p at 30fps