A page blueprint is the implementation of a document type in Confluence. It contains one ore more templates that form the base for new pages.
Page Blueprints and Space Blueprints
We need to differentiate between page blueprints, that build the basis for pages, and space blueprints, that are used to create spaces on a Confluence server. When speaking of blueprints one usually refers to page blueprints.
A space blueprints is a tool to help users bootstrap the space creation process. From a dialog users select a space blueprint and create a new space with a basic, blueprint-specific set of pages.
Wiki Markup is a special syntax used in Confluence to describe pages. At specific locations this syntax is the only way to add macros. This is the only use case for this kind of markup in the context of the projectdoc Toolbox.
References
A list of resources for more information on Confluence Blueprints.
Doctypes define properties and sections for documents. They are essentially Confluence Blueprints that help to create pages in your wiki based on templates.