Both posts and pages deal with presenting content on your website.
Posts allow its exact same content to be displayed in multiple locations. This is great for information that you want in multiple places on the website.
Pages are easier to visually understand because you go to the page you want to edit and all the content is created directly on the page with use of PAGE EDITOR. This is easiest, but you are not able to move the content later or have the content show up anywhere else on the website. If you need to move it, you must delete it and redo on your new page.