General-purpose maps show location of features. Thematic maps show the thematic concepts as well as their spatial attributes such as distances, patterns, directions. These two layers must 'cooperate' visually. The base layer provides locational information to the thematic overlay, but the former one should not carry too many features to avoid obstacting of the main theme of the map.
Maps are sometimes divided based on scale .
Large scale maps - used mainly for large scale topographic maps. This map type is one of the most popular techniques used for representing census variables within enumeration zones. The coloured or shaded areas are most often of statistical or administrative nature and are called chorograms. The most appropriate data would be characterized by its spatially discrete nature that can be confined by predefined borders. Continuous phenomena such as elevation or temperatures must not be mapped this way.