A detail map is a set of map data that can be loaded into a GPS navigation system.
Detail maps usually include a lot more information than a basemap. They commonly include streets of all sizes, rivers, lakes, parks, and even individual street addresses.
Some navigation systems come pre-loaded with detail maps for all of the United States and Canada. Others require that you load detail maps for particular areas using a personal computer.
The area covered by detailed maps may be limited by the amount of memory in your GPS navigation system.
This example screen from a Garmin StreetPilot shows detailed road data, including local streets and the individual ramps for a complex interchange.