Lowrance has licensed with different companies for the mapping that is loaded into their electronics. The HDS units have Insight mapping packages of your choice in them. When you purchase an HDS unit be sure to choose the correct mapping package for your needs.
The base map choice is for a person who prefers the mapping detail on a map card like Navionics, Lakemaster or Hot Maps for example.
The Nautic Insight is for navigable waters around the country like the San Joaquin Delta, the Colombia River and the coastline of the ocean here in the west.
The Lake Insight is the inland lakes around the country that have been surveyed and included in this mapping package.
The Insight USA is the Lake Insight and Nautic Insight all included in the preloaded mapping. This is the most common choice for bass fishermen out here who fish lakes and the Delta.
The lakes that are included on different cards or in units preloaded with mapping will differ and a list of the maps included should be looked at if you are looking for a specific lake.
Here is a link to a list of Insight Mapping lakes that are covered.