Ranking means as much as classification or ranking. Insearch engines, the ranking plays an important role because the ranking in the results pages( SERP) depends on it.
The search engine operators have various ranking algorithms with which they determine the ranking. Each ranking algorithm is subject to its own weighting. Which parameters, parameters and factors are in detail and how their weighting looks like is the secret of the search engine operators. The algorithms and parameters for ranking are changed and supplemented by the search engine operators. Therefore, the ranking of websites in different search engines is different.
Google used PageRank to evaluate the ranking of websites, Yahoo used WebRank, other search engines have their own designations. Newer ranking evaluations work with RankingIndex, VisibilityIndex, SEMrush Traffic, Moz Domain Authority, link popularity, reach in social networks (Google+, Facebook, Twitter) and Alexa TrafficRank. For all search engine drivers, each website and webpage is ranked individually.