The offline tour map is scaled to online maps and offers more detailed information than the online maps, along with the offline map bring you a peace of mind when you know where you are when internet is not available and you are in/outside the Zion National Park!
You can do lots more with the app such as recording then sharing your trips as named trails with friends, displaying your friends locations, contact sharing, note keeping, timer, fitness etc.
In case of getting lost, you can get your locations latitude/longitude and notify people so they can find you.