It has a lot more map data accessible and you can even overlay National Park Service maps, land ownership, accurate cell service grids, mountain biking trails, weather conditions and things like that.
I actually have all 3 apps though.
- Google Maps for on-road.
- Gaia Maps for topographic maps.
- Organic Maps as backup when there is no cell service and I need whatever additional information I can get my hands on. (Previously used OSM.)
(Not sponsored. This is the setup that has gotten me through the icy backroads of Iceland to the barren depths of Utah for 10+ years.)
Disclaimer: Just because you see a route on a map, digital or paper, does not mean it is passable today. Or it may be passable but at an extremely arduous pace. When you have access to detailed maps, they will show many more routes than you are used to but it does not mean they are all still usable.