Basically an encyclopedia differs from a dictionary in that a dictionary is fundamentally devoted to words and an encyclopedia offers information on various subjects, with data on and discussion of each subject identified. An almanac differs from an encyclopedia in that an almanac normally is issued periodically and includes ephemeral data applicable at the time of issue, while an encyclopedia is assembled from accumulated knowledge within a broader scope. An atlas is devoted to maps and charts.
The Columbia Electronic Encyclopedia, 6th ed. Copyright © 2012, Columbia University Press. All rights reserved.