A web-directory is a listing of different kinds of websites which is organized and broken down into different categories and sub-categories. The difference of web directories to search engines is that first is being managed by human editors per submission while the second is being crawled by automated programs such as bots.
If you want to learn more about web-directory, what it's for, that purpose does it serve, and its importance, the article on the link below has more.
Link: Directory Submission- Why is it Important?|Nextpinnacle
