Templates and cascading style sheets (CSS) are both methods for establishing consistent styles across multiple web pages in Dreamweaver. Templates allow for content to be edited within designated regions while keeping other regions like banners fixed, and changes made to the template are automatically reflected on all linked pages. CSS separates style rules from HTML content by defining styles in an external .css file linked to pages via <link> tags. This results in cleaner HTML and faster loading times compared to templates. Both achieve consistent styles but templates are easier to set up while CSS produces simpler code.