Monologue refers to a book or a paper created by an author. The author of solo works is usually a scholar or professional with certain authority or professional knowledge, and the content of solo works is more in-depth and professional.
Monographs refer to books or papers written by many authors. Co-authors are usually experts and scholars who have a certain reputation or authority in this field. They can discuss problems together and provide diverse views. The content of monographs is usually comprehensive, with more emphasis on field overview, latest research results and application of results.
Other differences include publication form, royalty distribution and other details, but in general, the main difference between singles and monographs lies in the identity of the author and the depth and breadth of the content.