Directories, unlike search engines, are a collection of specific resources. Depending on who is doing the choosing, directories can often yield “better” results to your query because of the “peer-reviewed” nature of the resources. This website, for example, is a directory, albeit a tiny (and sometimes silly) one. Directories sometimes also offer links to sites with databases that are not mined by traditional search engines (often refered to as the “Deep Web”).
diversity” heading, I was directed to a number of great sites. I like it!