Posts are things that are often changing or being added to. This site has many post sections including:
Satellite Chat Webinars
Each of our Blogs is its own post section
These are different than pages because we are constantly adding to them, we create lists of posts and we can then display on different pages through out the website.
Pages are used for more constant content. Most of our site is built with pages, but some pages will just display all of the posts from one section.