HDK features that are also in XDK:

• a number of table of contents options (more in v3.6)
  
• Styles, HDK generates a CSS based on the MSWord paragraph and character styles
  
• projects can process a "header" file or you can mock one up to control the names of the output HTML pages
  
• HTML pages can be split out of a single Word document using paragraph styles
  
• projects can include multiple Word documents.
  

Word Automatic numbering fix:

(from: Steve Hudson , HDK List MVP)
Just prior to publishing, make a copy of your document and open that copy.
Press Alt+F11 (opens the VBE), Ctrl+G (goto Immediate Window) and type

ActiveDocument.ConvertNumbersToText

This 'hard-codes' all lists in the document, numbers and bullet points.