

CoMaps has far less features, but that’s the point. Some people love the simplicity, they don’t need all the confusing and overwhelming options of osmand.
Osmand has some performance issues on some devices, but Comaps was generally much more responsive on any device I tried it.
CoMaps has 3d buildings. Its map is very nice, but this is subjective.
CoMaps aims to be fully FOSS, this was not true for its predecessors, OM and Maps.me. Osmand is not fully foss.
If you are perfectly happy with osmand you don’t really need it, but for new users who are only familiar with the very basic interfaces of other commercial map apps, it can be much more welcoming.
Do you want to import or record?
To import: star button -> import bookmarks and tracks. Then you can just pick it from your file browser. You can’t use it for navigation, it’s just displayed as an overlay.
To record: Hamburger menu -> Record track