The difference between a page and a post in wordpress CMS is very minimal. The way we approach deciding on which to use is based on content. When we are going to create a page that will not be altered that much through the course of time we select a page. When we create a page that will be interactive or constantly being added too we create a post. A post is more like a blog then a web page.
Below are 2 different tutorials on both pages and posts
How To Create A Post
How to Create A Page