Obtaining and setting up XSL tools and the DocBook XSL stylesheets, using the built-in options to control the XSL stylesheets, customizing the XSL stylesheets to match your design needs
Vex hides the raw XML tags from the user, providing instead a wordprocessor-like interface. Because of this, Vex is best suited for "document-style" XML documents such as XHTML and DocBook rather than "data-style" XML documents.
LyX is a document processor that encourages an approach to writing based on the structure of your documents (WYSIWYM), and not simply their appearance (WYSIWYG).