Google uses PageRank™ and hypertext-matching analysis to rank web pages. The difference between these two factors is explained by Google as follows:

Traditional search engines rely heavily on how often a word appears on a web page. Google uses PageRank™ to examine the entire link structure of the web and determine which pages are most important.

It then conducts hypertext-matching analysis to determine which pages are relevant to the specific search being conducted. By combining overall importance and query-specific relevance, Google is able to put the most relevant and reliable results first.

Hypertext-matching analysis involves the detailed assessment the entire content of a page.  This includes the fonts used, subdivisions and the precise location of each word. Google also analyzes the content of neighboring web pages to ensure the results returned are the most relevant to a user's query.

Google explains hypertext-matching analysis as follows:

Hypertext-Matching Analysis: Google's search engine also analyzes page content. However, instead of simply scanning for page-based text (which can be manipulated by site publishers through meta-tags), Google's technology analyzes the full content of a page and factors in fonts, subdivisions and the precise location of each word.

Google also analyzes the content of neighboring web pages to ensure the results returned are the most relevant to a user's query.