1. Search Engine :
Search Engine, as name suggests, is basically defined as application designed to carry out web searches and enables users to location information on WWW. Search engines are machine-driven and is used to find resources such as web pages, usenet forums, videos, etc., assigned to individual words.
Examples : Yahoo search, ASN, Live search, Google search, etc.
2. Subject Directory :
Subject Directory, as name suggests, is basically defined as collection of websites that include organized browsable subject categories and sub categories. Directories are human-driven and therefore have capability to deliver higher quality content. They are considered best for browsing and for search of more general nature and may include search engine for searching their own database.
Examples : Yahoo directory, Open directory, Google directory, etc.
Difference between Search Engine and Subject Directory : Search Engine Subject Directory
It is an online tool that is used to locate or search information on WWW. It is an online database of websites and online information set up by subject and category. It is generally maintained and reviewed by computer robotics. It is created, maintained and reviewed by human editors or experts. It allows users to find or locate information on internet using phrases and keywords. It allows users to find or locate information in internet using hierarchy. It locates and display relevant information based on formula and algorithm using automated software program. Directories are organized by human beings who discover new websites and relevant information by exploring internet themselves and by reviewing submitted websites. They are used mainly for research, shopping and entertainment. They are used mainly to search broad topics, current events, organization or business homepages, etc. They are bigger than directories as it includes billions of web pages. They tend to be smaller than search engine databases. It is considered good to look for specific or complex information and its advanced features allow to refine search and improve results. It is considered best if one wants to browse broad topics and it can give good idea about amount and type of web-based information on topic. User search content or information on database of search engine. User search only websites included and identified by directory.