Dreamweaver allows you to build custom websites in plain old HTML/CSS. Wordpress is a Content Management System
, which means you will make "posts" (similar to how you posted here) to appear on your website. For a dynamic website, a CMS is a must. However, there is a learning curve involved since you will need to make themes/templates to work with the Wordpress CMS.
CMS systems have many
advantages over regular HTML/CSS coding in that they make it easier to post content and add pages to your site, allow you to create a very dynamic site (such as allowing users to contribute content/images/videos), addons, commenting system, user registration/login, etc.
You could even go one step more and create your own CMS system. But that would require alot of knowledge in PHP and databases.
Also, here is a list of Features for Wordpress: http://wordpress.org/about/features/