One of the main differences between Help+Manual and a word processor is that in a word processor you work in a single document. In a Help+Manual project, each topic is an independent file that is like a word processor document. However, Help+Manual manages all these files as though they were a single document. For example, you can perform search and replace operations globally in all your topic files.
You can move topics around in the Table of Contents (TOC) section of the Project Explorer with the keyboard and the mouse and you can also change the "level" of topics in the TOC tree hierarchy.