We recently clarified the differences between "Revisions" and "Versions":

• Revisions are successive updates to content (eg. latest revision compared to last week's revision).
• Versions are alternative presentations of the same content (eg. English version and French version).
  

"Publishing" is now equivalent to "approving a revision for public view".  Publishing a page approves the newest revisions of every content item on that page.  Publishing a whole section approves the newest revisions of every item in that section.

Previously, some content items were ignored by the publishing tools (eg. text items that were inlined into the main HTML instead of written out as separate files).  Now these items are marked as published even though they are not written out to files.  That publish timestamp serves as an indication that the revision is approved for public view.  When creating dynamic page views for the public, we only use the published versions of all content items, including inlined text content.  That means  that updates to the page body will NOT appear publicly until an  administrator has published the page (even though publishing a dynamic page may not result in any files actually being written to disk).