One of the first things we train our clients on in WordPress is the difference between posts and pages. Although you create them in much the same way, they have very fundamental differences.
WordPress was originally created as a blogging platform. That is what posts are generally used for. They are displayed on the blog in reverse chronological order, so that the latest post is displayed first. They will also be syndicated through an RSS feed so that followers of the blog can be updated on new posts. Posts can be used for personal blogs, news, articles, etc.
Posts are also more social. Typically users can comment on your posts, and easily share them on social networks.
To add a post in WordPress, you simply click the Posts, then Add New link in the WordPress menu.
Pages are more permanent and static. They don’t change much. They are used for your typical content pages such as About Us, Services, Contact, etc. Your pages will usually be added to the sites navigation, rather than in chronological order. You wouldn’t normally have comments open on pages either.
To add a page, you would click Pages, then Add New in the WordPress menu. You may also have to add your new page to your site’s navigation menu once the page is created.