how metasearch engines differ from general search engines

how metasearch engines works : how different are they as compared to traditional search engines 

 Metesearch engines  are  search engine aggregator, which extracts the search results from different search engines and presents the users with the top ranked sites .. Metasearch engines do not maintain databases of its own, but rather it extracts  and combines data from results from  several other search engines  and displays it in a search engine SERP format.

One of the biggest advantages  that metasearch engines have is that " They often combine the best search results across many search engines and displays the best results based  on the user query for the keyword"

 The more results  that can be seen in one place the better it is for users .Among the top 2 biggest metasearch engines are 1) Dogpile and Duckduckgo.

While Dogpile pulls results from Yahoo and Google in one place, Duckduckgo gives you a overview of search results without creating a personalised feed of your search rankings.This creates a more filtering approach  to all the indexed data gathered from the other search engine sources.The ads appear at the top and bottom  with organic search  called " web results" appearing in the middle .The Biggest proposition which  duckduckgo provides  is the fact that  its the only known search engine that does not track user behavior 

After pulling the necessary data from known search engines, The metasearch engines , retains the top  search rankings from the separate search engines and presents the user with top ranked sites  This is different from running an algorithm  to find the best sites for a keyword by creating an index