I was randomly browsing about ranking algorithms and came across this page which explains the difference between popularity and the trustworthiness of a webpage. Google or Bing may follow different page ranking algorithm to rank the web pages. Personalization would also play an important role in determining the ranking of the webpage.
The popularity of the web page is calculated in terms of mozRank
MozRank is calculated at a scale of between 1 and 10 with respect to the popularity of the website. The underlying principle is very easy to understand. The more links a page receives, the better it will be popular and obviously it will increase the ranking of the site.
In the similar line, trustworthiness of a webpage is calculated in terms of mozTrust
mozTrust is another important factor which would influence the ranking of a page in the search engine results. This feature enumerates the confidence of a page relative to the other page found on the web. Again, the logic is quite similar. If a page gets a link from another page which was considered "trusted" by the engine, it is rated on a higher scale. The trusted sites can be any of the educational institutions like ASU, government websites, company sites etc.
For getting more information and technical aspect of these features, please refer this site.
http://www.seomoz.org/learn-seo/mozrank
http://www.seomoz.org/learn-seo/moztrust
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Sathish
