Branch works: These are centered on a single shiny dime, and the rest of the book is padded with further explanations, real-world examples, etc.
Tree works: These explain an entire system of thought, end-to-end. The shiny dime is still there (or should be, if the book is good), but it may be more elaborate.
Narrative works: These are biographies, memoirs, etc. These tell you about the history of something or someone. Example: Steve Jobs’ biography.