Moz trust and Page rank are different they use different methods to score the specific values I have put together some information and sources for you to read up more to have a better answer:
**How is MozTrust Scored? ** We determine MozTrust by calculating link “distance” between a given page and a seeded trust source on the Internet. (Think of this like six degrees of separation – the closer you are linked to a trusted website, the more trust you have yourself.)
We score MozTrust on a logarithmic scale between 1 and 10. Thus, it's much easier to improve from a MozTrust of 3 to 4 than it is to improve from 8 to 9. How can MozTrust be improved?MozTrust can be improved by getting links from other sites with high MozTrust such as goverment institutions and universities.
Further information:
http://www.seomoz.org/learn-seo/moztrust
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PageRank is a numeric value that represents how important a page is on the web. Google figures that when one page links to another page, it is effectively casting a vote for the other page. The more votes that are cast for a page, the more important the page must be. Also, the importance of the page that is casting the vote determines how important the vote itself is. Google calculates a page's importance from the votes cast for it. How important each vote is is taken into account when a page's PageRank is calculated. PageRank is Google's way of deciding a page's importance. It matters because it is one of the factors that determines a page's ranking in the search results. It isn't the only factor that Google uses to rank pages, but it is an important one. From here on in, we'll occasionally refer to PageRank as "PR". Further information:
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http://www.webworkshop.net/pagerank.html