If Google Page Rank, that appears in the Google Toolbar, is the measure of a particular webpage’s popularity or importance, mainly, base on the number of inbound links as computed using the pagerank formula, Alexa Traffic Rank, on the other hand, is the measure of a website’s traffic, including traffic from its sub-domains, based on a three months of aggregated historical traffic data from Alexa Toolbar users.

Though Alexa’s objective is to show the actual traffic of a particular website, the number that it shows serves as only a random sample of the actual traffic of that website. This is because only a small percentage of internet users are using Alexa toolbar, where Alexa Traffic Ranking algorithm solely base its computation and ranking. In addition to this, Alexa Toolbar works only with the Internet Explorer browser and on Windows operating systems. The Alexa Toolbar also turns itself off on secure pages (https:). It also counts traffic from advertisement. Thus, Alexa Traffic Rank has a considerable percentage of error and doesn’t really reflect the exact and actual traffic of a website. But since the traffic was base on a random sample and assuming that the sampling is close to uniform, it could still be a good bases for giving idea of the amount of traffic and traffic ranking, just always remember that it has some percentage of error.

On the other hand, Google Pagerank may be accurate in the value of pagerank that it shows, assuming that the computation using the page ranking formula is updated and correct, however, it may not show the real rank of popularity and importance of a particular webpage. This is because of the widespread practice of link exchange, link buying and link spamming which would result in an unnatural growth or increase of inbound links, and thereby, page rank.

Google Pagerank and Alexa Traffic Rank though both attempted to rank the websites, they, on the other hand, are entirely different in their objective, (Google rank webpages according to its popularity and importance based on inbound links while Alexa rank the websites according to its traffic, which is randomly sampled), and in the method, and algorithm used, considering the loop holes and the imperfectness, incompleteness and unreliability of the data, which they base the ranking. That is why it is more often that they show a different and contradicting statistics, specially, for a relatively small and new websites.