A CITATION STYLE dictates how citation information is ordered. There are a number of citation styles such as MLA, APA or Chicago Turabian.
A CITATION reflects all of the information a person would need to locate a particular source. For example, basic citation information for a book consists of the author's name, the title of the book, name of the publisher, place of publication, and copyright date.
An IN-TEXT CITATION consists of just enough information to correspond to a source's full citation in a Reference or Works Cited list.
A REFERENCE OR WORKS CITED list presents citations for those sources referenced in a particular paper, presentation, or other composition.