Comment by apt-apt-apt-apt

For others curious like I was, it seems he hired a cartographer to render essentially a set of huge, nice-looking, custom map images with details like hiking trails that Apple Maps doesn't have.

So unlike Apple Maps, which is dynamically rendered, it basically shows image tiles. It allows for a nicer-looking, more detailed map, but affects things like needing separate downloads for different zoom levels, rotation, updatability.