An atlas is a collection of maps, most often bound together into book form. Additionally, atlases may include facts about the area, pictures of interest about the area, and informational tables.
A thematic atlas deals with a particular subject in relation to a specific area. Thematic atlases may include such information as the area's history, religions, agriculture or climate.
Encyclopedias primarily contain textual, or narrative, information along with associated illustrations. An encyclopedia can include anywhere from a single volume to over a hundred volumes; some may contain a form of atlas, that is a collection of maps, as illustration of included subjects.
Encyclopedias have two primary goals: providing up-to-date knowledge on included subjects, and making that information conveniently accessible. Encyclopedias strive for ease of use, such as through arranging information in alphabetical order, and also strive to communicate information in a way ordinary people can understand easily.
An encyclopedia takes the form of a variety of different articles incorporated into one or more bound volumes or, for online encyclopedias, a website. Often, experts in the field covered by the encyclopedia author the various articles.