Difference between a search engine and a directory
A search engine, such as Yahoo or Google, is an online tool that helps users of the Internet find the sites and information they're looking for. Most search engines use automated programs (sometimes called spiders) to look for relevant information based on keywords entered by the user.
A search directory, such as Yahoo Directory, is a catalog of websites organized by category to allow users to easily browse for the information they need. Unlike search engines, which locate and display relevant information based on a formula or algorithm using an automated software program, search directories are organized by real people who discover new sites and relevant information by exploring the Internet themselves and by reviewing submitted sites.
Both search engines and directories can help drive customers to your website. Neither guarantees that your site will be included in their listings.