addition / edition are similar-sounding terms with different meanings (referred to as homophones). To better understand the differences, see below for definitions, pronunciation guides, and example sentences using each term. 👇
addition: (noun) a component that is added to something to improve it. (noun) the act of adding one thing to another. (noun) a quantity that is added. (noun) a suburban area laid out in streets and lots for a future residential area.
edition: (noun) the form in which a text (especially a printed book) is published. (noun) all of the identical copies of something offered to the public at the same time. (noun) an issue of a newspaper.
addition: ah·d·IH·sh·ah·n
edition: ah·d·IH·sh·ah·n
(Examples are Wikipedia snippets under the CC ShareAlike 3.0 license. Definitions drawn from WordNet.)